ADC07D1520_技术文档

ADC07D1520

Low Power, 7-Bit, Dual 1.5 GSPS or Single 3.0 GSPS A/D Converter

General Description

Features

The ADC07D1520 is a dual, low power, high performance

CMOS analog-to-digital converter. The ADC07D1520 digi-

tizes signals to 7 bits of resolution at sample rates up to 1.5

GSPS. Its features include a test pattern output for system

debug, a clock phase adjust, and selectable output demulti-

plexer modes. This device is guaranteed to have no missing

codes over the full operating temperature range. The unique

folding and interpolating architecture, the fully differential

comparator design, the innovative design of the internal sam-

ple-and-hold amplifier and the self-calibration scheme enable

a very flat response of all dynamic parameters beyond

Nyquist, producing a high 6.8 Effective Number of Bits

(ENOB) with a 748 MHz input signal and a 1.5 GHz sample

rate while providing a 10^-18Code Error Rate (C.E.R.) Output

formatting is offset binary and the Low Voltage Differential

Signaling (LVDS) digital outputs are compatible with IEEE

1596.3-1996, with the exception of an adjustable common

mode voltage between 0.8V and 1.2V.

Single +1.9V ±0.1V Operation

●

Interleave Mode for 2x Sample Rate

Multiple ADC Synchronization Capability

Adjustment of Input Full-Scale Range, Clock Phase, and

Offset

Choice of SDR or DDR Output Clocking

●

1:1 or 1:2 Selectable Output Demux

Second DCLK Output

Duty Cycle Corrected Sample Clock

Test pattern

●

Key Specifications

Resolution

7 Bits

1.5 GSPS (max)

10^-18(typ)

6.8 Bits (typ)

±0.15 LSB (typ)

●

Max Conversion Rate

Code Error Rate

ENOB @ 748 MHz Input

DNL

Each converter has a selectable output demultiplexer which

feeds two LVDS buses. If the 1:2 Demultiplexed Mode is se-

lected, the output data rate is reduced to half the input sample

rate on each bus. When Non-Demultiplexed Mode is selected,

the output data rate on channels DI and DQ is at the same

rate as the input sample clock. The two converters can be

interleaved and used as a single 3 GSPS ADC.

Power Consumption (Non-DES Mode)

Operating in 1:2 Demux Mode

Power Down Mode

1.9 W (typ)

2.5 mW (typ)

—

Applications

The converter typically consumes less than 3.5 mW in the

Power Down Mode and is available in a leaded or lead-free,

128-pin, thermally enhanced, exposed pad LQFP and oper-

ates over the Industrial (-40°C ≤ T_A≤ +85°C) temperature

range.

Direct RF Down Conversion

●

Digital Oscilloscopes

Satellite Set-top boxes

Communications Systems

Test Instrumentation

●

Ordering Information

Industrial Temperature Range (-40°C < T_A< +85°C)

NS Package

ADC07D1520CIYB/NOPB

Lead-free 128-Pin Exposed Pad LQFP

PRODUCTION DATA information is current as of

publication date. Products conform to specifications per

the terms of the Texas Instruments standard warranty.

Production processing does not necessarily include

testing of all parameters.

301941 SLAS881A

ADC07D1520

Block Diagram

30194153

2

ADC07D1520

Pin Configuration

30194101

Note: The exposed pad on the bottom of the package must be soldered to a ground plane to ensure rated performance.

3

ADC07D1520

Pin Descriptions and Equivalent Circuits

Pin Functions

Pin No.

Symbol

Equivalent Circuit

Description

Output Voltage Amplitude and Serial Interface Clock. Tie this

pin logic high for normal differential DCLK and data

amplitude. Ground this pin for a reduced differential output

amplitude and reduced power consumption. See 1.1.6 The

LVDS Outputs. When the Extended Control Mode is

enabled, this pin functions as the SCLK input which clocks

in the serial data. See 1.2 NON-EXTENDED AND

EXTENDED CONTROL MODE for details on the Extended

Control Mode. See 1.3 THE SERIAL INTERFACE for

description of the serial interface.

3

OutV / SCLK

Power Down Q-channel. A logic high on the PDQ pin puts

only the Q-channel into the Power Down Mode.

29

PDQ

DCLK Edge Select, Double Data Rate Enable and Serial

Data Input. This input sets the output edge of DCLK+ at

which the output data transitions. See 1.1.5.2 OutEdge and

Demultiplex Control Setting. When this pin is floating or

connected to 1/2 the supply voltage, DDR clocking is

enabled. When the Extended Control Mode is enabled, this

pin functions as the SDATA input. See 1.2 NON-EXTENDED

AND EXTENDED CONTROL MODE for details on the

Extended Control Mode. See 1.3 THE SERIAL

OutEdge / DDR /

SDATA

4

INTERFACE for description of the serial interface.

DCLK Reset. When single-ended DCLK_RST is selected by

floating or setting pin 52 logic high, a positive pulse on this

pin is used to reset and synchronize the DCLK outputs of

multiple converters. See 1.5 MULTIPLE ADC

SYNCHRONIZATION for detailed description. When

differential DCLK_RST is selected by setting pin 52 logic low,

this pin receives the positive polarity of a differential pulse

signal used to reset and synchronize the DCLK outputs of

multiple converters.

DCLK_RST /

DCLK_RST+

15

Power Down Pins. A logic high on the PD pin puts the entire

device into the Power Down Mode.

26

30

PD

Calibration Cycle Initiate. A minimum t_{CAL_L}input clock

cycles logic low followed by a minimum of t_{CAL_H}input clock

cycles high on this pin initiates the self calibration sequence.

See 2.4.2 Calibration for an overview of calibration and

2.4.2.2 On-Command Calibration for a description of on-

command calibration. The calibration cycle may similarly be

initiated via the CAL bit in the Calibration register (0h).

CAL

4

ADC07D1520

Pin Functions

Pin No.

Symbol

Equivalent Circuit

Description

Full Scale Range Select, Alternate Extended Control Enable

and DCLK_RST-. This pin has three functions. It can

conditionally control the ADC full-scale voltage, enable the

Extended Control Mode, or become the negative polarity

signal of a differential pair in differential DCLK_RST mode.

If pin 52 is floating or at logic high and pin 41 is floating, this

pin can be used to set the full-scale-range or can be used as

an alternate Extended Control Mode enable pin. When used

as the FSR pin, a logic low on this pin sets the full-scale

differential input range to a reduced V_INinput level . A logic

high on this pin sets the full-scale differential input range to

a higher V_INinput level. See Converter Electrical

FSR/ALT_ECE/

DCLK_RST-

14

Characteristics. To enable the Extended Control Mode,

whereby the serial interface and control registers are

employed, allow this pin to float or connect it to a voltage

equal to V_A/2. See 1.2 NON-EXTENDED AND EXTENDED

CONTROL MODE for information on the Extended Control

Mode. Note that pin 41 overrides the Extended Control Mode

enable of this pin. When pin 52 is held at logic low, this pin

acts as the DCLK_RST- pin. When in differential DCLK_RST

mode, there is no pin-controlled FSR and the full-scale-range

is defaulted to the higher V_INinput level.

(Note 17)

Calibration Delay, Dual Edge Sampling and Serial Interface

Chip Select. In non-extended control mode, this pin functions

as the Calibration Delay select. A logic high or low the

number of input clock cycles after power up before

calibration begins (See 1.1.1 Calibration). When this pin is

floating or connected to a voltage equal to V_A/2, DES (Dual

Edge Sampling) Mode is selected where the I-channel is

sampled at twice the input clock rate and the Q-channel is

ignored. See 1.1.5.1 Dual-Edge Sampling. In extended

control mode, this pin acts as the enable pin for the serial

interface input and the CalDly value becomes "0" (short

delay with no provision for a long power-up calibration delay).

(Note 17)

127

CalDly / DES / SCS

Differential clock input pins for the ADC. The differential clock

signal must be a.c. coupled to these pins. The input signal is

sampled on the falling edge of CLK+. See 1.1.2 Acquiring

the Input for a description of acquiring the input and 2.3 THE

CLOCK INPUTS for an overview of the clock inputs.

18

19

CLK+

CLK-

5

ADC07D1520

Pin Functions

Pin No.

Symbol

Equivalent Circuit

Description

Analog signal inputs to the ADC. The differential full-scale

input range of this input is programmable using the FSR pin

14 in Non-Extended Control Mode and the Input Full-Scale

Voltage Adjust register in the Extended Control Mode. Refer

to the V_INspecification in the Converter Electrical

Characteristics for the full-scale input range in the Non-

Extended Control Mode. Refer to 1.4 REGISTER

DESCRIPTION for the full-scale input range in the Extended

Control Mode.

V_INI-

V_INI+

10

11

22

23

V_INQ+

V_INQ−

Common Mode Voltage. This pin is the common mode

output in d.c. coupling mode and also serves as the a.c.

coupling mode select pin. When d.c. coupling is used at the

analog inputs, the voltage output at this pin is required to be

the common mode input voltage at V_IN+ and V_IN−. When a.c.

coupling is used, this pin should be grounded. This pin is

capable of sourcing or sinking 100 μA. See 2.2 THE

ANALOG INPUT.

V_CMO

7

Bandgap output voltage. This pin is capable of sourcing or

V_BG

31

sinking 100 μA and can drive a load up to 80 pF.

Calibration Running indication. This pin is at a logic high

when calibration is running.

126

CalRun

(Note 17)

External bias resistor connection. Nominal value is 3.3 kΩ

(±0.1%) to ground. See 1.1.1 Calibration.

R_EXT

32

Temperature Diode Positive (Anode) and Negative

(Cathode). These pins may be used for die temperature

measurements, however no specified accuracy is implied or

guaranteed. Noise coupling from adjacent output data

signals has been shown to affect temperature

measurements using this feature. See 2.6.2 Thermal

Management.

34

35

Tdiode_P

Tdiode_N

Extended Control Enable. This pin always enables or

disables Extended Control Mode. When this pin is set logic

high, the Extended Control Mode is inactive and all control

of the device must be through control pins only . When it is

set logic low, the Extended Control Mode is active. This pin

overrides the Extended Control Enable signal set using pin

14.

41

ECE

6

ADC07D1520

Pin Functions

Pin No.

Symbol

Equivalent Circuit

Description

DCLK_RST select. This pin selects whether the DCLK is

reset using a single-ended or differential signal. When this

pin is floating or logic high, the DCLK_RST operation is

single-ended and pin 14 functions as FSR/ALT_ECE. When

this pin is logic low, the DCLK_RST operation becomes

differential with functionality on pin 15 (DCLK_RST+) and pin

14 (DCLK_RST-). When in differential DCLK_RST mode,

there is no pin-controlled FSR and the full-scale-range is

defaulted to the higher V_INinput level. When pin 41 is set

logic low, the Extended Control Mode is active and the Full-

Scale Voltage Adjust registers can be programmed.

(Note 17)

52

DRST_SEL

83 / 78

84 / 77

85 / 76

86 / 75

89 / 72

90 / 71

91 / 70

92 / 69

93 / 68

94 / 67

95 / 66

96 / 65

100 / 61

101 / 60

DI6− / DQ6−

DI6+ / DQ6+

DI5− / DQ5−

DI5+ / DQ5+

DI4− / DQ4−

DI4+ / DQ4+

DI3− / DQ3−

DI3+ / DQ3+

DI2− / DQ2−

DI2+ / DQ2+

DI1− / DQ1−

DI1+ / DQ1+

DI0− / DQ0−

DI0+ / DQ0+

I- and Q-channel LVDS Data Outputs that are not delayed in

the output demultiplexer. Compared with the DId and DQd

outputs, these outputs represent the later time samples.

These outputs should always be terminated with a 100Ω

differential resistor.

In Non-demultiplexed Mode, only these outputs are active.

104 / 57

105 / 56

106 / 55

107 / 54

111 / 50

112 / 49

113 / 48

114 / 47

115 / 46

116 / 45

117 / 44

118 / 43

122 / 39

123 / 38

DId6− / DQd6−

DId6+ / DQd6+

DId5− / DQd5−

DId5+ / DQd5+

DId4− / DQd4−

DId4+ / DQd4+

DId3− / DQd3−

DId3+ / DQd3+

DId2− / DQd2−

DId2+ / DQd2+

DId1− / DQd1−

DId1+ / DQd1+

DId0− / DQd0−

DId0+ / DQd0+

I- and Q-channel LVDS Data Outputs that are delayed by

one CLK cycle in the output demultiplexer. Compared with

the DI and DQ outputs, these outputs represent the earlier

time sample. These outputs should always be terminated

with a 100Ω differential resistor.

In Non-demultiplexed Mode, these outputs are disabled and

are high impedance. When disabled, these outputs must be

left floating.

Out Of Range, second Data Clock output. When functioning

as OR+/-, a differential high at these pins indicates that the

differential input is out of range (outside the range ±V_IN/2 as

programmed by the FSR pin in Non-extended Control Mode

or the Input Full-Scale Voltage Adjust register setting in the

Extended Control Mode). This single out of range indication

is for both the I- and Q-channels, unless PDQ is asserted, in

which case it only applies to the I-channel input. When

functioning as DCLK2+/-, DCLK2 is the exact replica of

DCLK and outputs the same signal at the same rate. The

functionality of these pins is selectable in Extended Control

Mode only; default is OR+/-.

79

80

OR+/DCLK2+

OR-/DCLK2-

7

ADC07D1520

Pin Functions

Pin No.

Symbol

Equivalent Circuit

Description

Data Clock. Differential Clock outputs used to latch the

output data. Delayed and non-delayed data outputs are

supplied synchronously to this signal. In 1:2 Demux Mode,

this signal is at 1/2 the input clock rate in SDR mode and at

1/4 the input clock rate in the DDR mode. In the Non-demux

Mode, DCLK can only be in DDR mode and is at 1/2 the input

clock rate. By default, the DCLK outputs are not active during

the termination resistor trim section of the calibration cycle.

If a system requires DCLK to run continuously during a

calibration cycle, the termination resistor trim portion of the

cycle can be disabled by setting the Resistor Trim Disable

(RTD) bit to logic high in the Extended Configuration

Register. This disables all subsequent termination resistor

trims after the initial trim which occurs during power-on

calibration. This output is not recommended as a system

clock unless the resistor trim is disabled.

81

82

DCLK-

DCLK+

2, 5, 8, 13,

16, 17, 20,

25, 28, 33,

128

V_A

Analog power supply pins. Bypass these pins to ground.

40, 51, 62,

73, 88, 99,

110, 121

Output Driver power supply pins. Bypass these pins to DR

GND.

V_DR

GND

1, 6, 9, 12,

21, 24, 27

Ground return for V_A.

42, 53, 64,

74, 87, 97,

108, 119

Ground return for V_DR

.

DR GND

NC

63, 98, 109,

120

No Connection. Make no connection to these pins.

36 / 37

58 / 59

103 / 102

125 / 124

Reserved. These pins may be left unconnected and floating,

or as recommended in 2.5.1 Terminating RSV Pins.

RSV+ / RSV-

8

ADC07D1520

Absolute Maximum Ratings

(Note 1, Note 2)

If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for

availability and specifications.

Supply Voltage (V_A, V_DR

)

2.2V

0V to 100 mV

Supply Difference

V_DR- V_A

Voltage on Any Input Pin

(Except V_IN+, V_IN- )

−0.15V to (V_A+0.15V)

Voltage on V_IN+, V_IN-

(Maintaining Common Mode)

-0.15V to 2.5V

Ground Difference

|GND - DR GND|

0V to 100 mV

±25 mA

Input Current at Any Pin (Note 3)

Package Input Current (Note 3)

±50 mA

Maximum Package Power Dissipation at T_A≤ 85°C

2.35 W

ESD Susceptibility (Note 4)

Human Body Model

Machine Model

ꢀ

2500V

250V

Charged Device Model

1000V

Storage Temperature

−65°C to +150°C

Operating Ratings

(Note 1, Note 2)

Ambient Temperature Range

Supply Voltage (V_A)

−40°C ≤ T_A≤ +85°C

+1.8V to +2.0V

Driver Supply Voltage (V_DR

)

+1.8V to V_A

Analog Input Common Mode Voltage

V_CMO±50 mV

V_IN+, V_IN- Voltage Range (Maintaining Common Mode)

0V to 2.15V

(100% duty cycle)

0V to 2.5V

(10% duty cycle)

Ground Difference

(|GND - DR GND|)

0V

0V to V_A

CLK Pins Voltage Range

Differential CLK Amplitude

0.4V_P-Pto 2.0V_P-P

Package Thermal Resistance

θ_JC

Package

θ_JA

Top of Package

Thermal Pad

128-Lead,

Exposed Pad LQFP

26°C / W

10°C / W

2.8°C / W

For soldering information please refer to http://www.ti.com/lit/an/snoa549c/snoa549c.pdf.(Note 5)

9

ADC07D1520

Converter Electrical Characteristics

The following specifications apply after calibration for V_A= V_DR= +1.9V; OutV = 1.9V; V_INFSR (a.c. coupled) = differential 870

mV_P-P; C_L= 10 pF; Differential, a.c. coupled Sine Wave Input Clock, f_CLK= 1.5 GHz at 0.5 V_P-Pwith 50% duty cycle; V_BG= Floating;

Non-extended Control Mode; SDR Mode; R_EXT= 3300 Ω ±0.1%; Analog Signal Source Impedance = 100 Ω Differential; 1:2 De-

multiplex Mode; Duty Cycle Stabilizer on. Boldface limits apply for T_A= T_MINto T_MAX. All other limits T_A= 25°C, unless otherwise

noted. (Note 6, Note 7, Note 16, Note 18)

Typical

(Note 8)

Units

(Limits)

Symbol

Parameter

Conditions

Limits

STATIC CONVERTER CHARACTERISTICS

Integral Non-Linearity

(Best fit)

DC Coupled, 1 MHz Sine Wave Over-

ranged

INL

±0.3

±0.9

±0.6

7

LSB (max)

Bits

DC Coupled, 1 MHz Sine Wave Over-

ranged

DNL

Differential Non-Linearity

±0.15

Resolution with No Missing

Codes

V_OFF

Offset Error

−0.75

±45

LSB

mV

V_OFF_ADJ

PFSE

Input Offset Adjustment Range Extended Control Mode

Positive Full-Scale Error

Negative Full-Scale Error

(Note 9)

±25

±15

mV (max)

%FS

NFSE

FS_ADJ

Full-Scale Adjustment Range Extended Control Mode

±20

1:2 DEMUX NON-DES MODE, DYNAMIC CONVERTER CHARACTERISTICS; F_CLK= 1.5 GHZ

FPBW

C.E.R.

Full Power Bandwidth

Code Error Rate

Non-DES Mode

2.0

10⁻¹⁸

±0.5

±1.0

6.8

GHz

Error/Sample

dBFS

Bits (min)

Bits

d.c. to 748 MHz

Gain Flatness

d.c. to 1.5 GHz

f_IN= 373 MHz, V_IN= FSR − 0.5 dB

f_IN= 748 MHz, V_IN= FSR − 0.5 dB

f_IN= 373 MHz, V_IN= FSR − 0.5 dB

f_IN= 748 MHz, V_IN= FSR − 0.5 dB

f_IN= 373 MHz, V_IN= FSR − 0.5 dB

f_IN= 748 MHz, V_IN= FSR − 0.5 dB

f_IN= 373 MHz, V_IN= FSR − 0.5 dB

f_IN= 748 MHz, V_IN= FSR − 0.5 dB

f_IN= 373 MHz, V_IN= FSR − 0.5 dB

f_IN= 748 MHz, V_IN= FSR − 0.5 dB

f_IN= 373 MHz, V_IN= FSR − 0.5 dB

f_IN= 748 MHz, V_IN= FSR − 0.5 dB

f_IN= 373 MHz, V_IN= FSR − 0.5 dB

f_IN= 748 MHz, V_IN= FSR − 0.5 dB

f_IN1= 365 MHz, V_IN= FSR − 7 dB

f_IN2= 375 MHz, V_IN= FSR − 7 dB

(V_IN+) − (V_IN−) > + Full Scale

6.3

39.5

40.8

-47

ENOB

SINAD

SNR

Effective Number of Bits

6.8

43

dB (min)

dB

Signal-to-Noise Plus Distortion

Ratio

43

43.2

−55

−60

−63

−58

−67

57

dB (min)

dB

Signal-to-Noise Ratio

dB (max)

dB

THD

Total Harmonic Distortion

Second Harmonic Distortion

Third Harmonic Distortion

Spurious-Free Dynamic Range

Intermodulation Distortion

Out of Range Output Code

dB

2nd Harm

3rd Harm

SFDR

IMD

dB

45.5

dB (min)

dB

61

−50

dB

127

0

(V_IN+) − (V_IN−) < − Full Scale

1:4 DEMUX DES MODE, DYNAMIC CONVERTER CHARACTERISTICS; F_CLK= 1.5 GHZ

FPBW

ENOB

Full Power Bandwidth

DES Mode

1.3

6.7

GHz

Bits

f_IN= 748 MHz, V_IN= FSR − 0.5 dB

Effective Number of Bits

Signal to Noise Plus Distortion

Ratio

f_IN= 748 MHz, V_IN= FSR − 0.5 dB

SINAD

42

dB

f_IN= 748 MHz, V_IN= FSR − 0.5 dB

SNR

Signal to Noise Ratio

43

dB

THD

Total Harmonic Distortion

Second Harmonic Distortion

−52

−57

2nd Harm

10

ADC07D1520

Typical

(Note 8)

Units

(Limits)

Symbol

Parameter

Conditions

Limits

f_IN= 748 MHz, V_IN= FSR − 0.5 dB

3rd Harm

SFDR

Third Harmonic Distortion

−57

52

dB

Spurious Free Dynamic Range

ANALOG INPUT AND REFERENCE CHARACTERISTICS

mV_P-P(min)

mV_P-P(max)

mV_P-P(min)

mV_P-P(max)

V (min)

590

730

FSR pin 14 Low

(Note 12)

650

870

Full Scale Analog Differential

Input Range

V_IN

800

FSR pin 14 High

940

V_CMO− 0.05

V_CMO+ 0.05

V_CMI

V_CMO

Common Mode Input Voltage

V (max)

Analog Input Capacitance,

Normal operation

(Note 10, Note 11)

Differential

0.02

1.6

pF

Each input pin to ground

pF

C_IN

Differential

0.08

2.2

pF

Analog Input Capacitance,

DES Mode (Note 10, Note 11)

Each input pin to ground

94

Ω (min)

Ω (max)

R_IN

Differential Input Resistance

100

106

ANALOG OUTPUT CHARACTERISTICS

0.95

1.45

V (min)

V (max)

V_CMO

I_CMO= ±100 µA

Common Mode Output Voltage

1.26

118

Common Mode Output Voltage

Temperature Coefficient

TC V_CMO

V_{CMO_LVL}

T_A= −40°C to +85°C

ppm/°C

V_A= 1.8V

V_A= 2.0V

0.60

0.66

V

V_CMOinput threshold to set D.C.

Coupling mode

Maximum V_CMOLoad

Capacitance

C_LOADV_CMO

80

pF

1.20

1.34

V (min)

V (max)

Bandgap Reference Output

Voltage

V_BG

I_BG= ±100 µA

1.26

28

T_A= −40°C to +85°C,

I_BG= ±100 µA

Bandgap Reference Voltage

Temperature Coefficient

TC V_BG

ppm/°C

pF

Maximum Bandgap Reference

load Capacitance

C_LOADV_BG

80

CHANNEL-TO-CHANNEL CHARACTERISTICS

Offset Match

1

LSB

Positive Full-Scale Match

Negative Full-Scale Match

Phase Matching (I, Q)

Zero offset selected in Control Register

f_IN= 1.5 GHz

1

LSB

< 1

Degree

Crosstalk from I-channel

(Aggressor) to Q-channel

(Victim)

Aggressor = 867 MHz F.S.

Victim = 100 MHz F.S.

X-TALK

−65

dB

Crosstalk from Q-channel

(Aggressor) to I-channel

(Victim)

Aggressor = 867 MHz F.S.

Victim = 100 MHz F.S.

LVDS CLK INPUT CHARACTERISTICS (Typical specs also apply to DCLK_RST)

V_P-P(min)

V_P-P(max)

V_P-P(min)

V_P-P(max)

V

0.4

2.0

0.4

2.0

Sine Wave Clock

0.6

V_ID

Differential Clock Input Level

Square Wave Clock

V_OSI

C_IN

Input Offset Voltage

1.2

0.02

1.5

Differential

pF

Input Capacitance

(Note 10, Note 11)

Each input to ground

pF

11

ADC07D1520

Typical

(Note 8)

Units

(Limits)

Symbol

Parameter

Conditions

Limits

DIGITAL CONTROL PIN CHARACTERISTICS

OutV, DCLK_RST, PD, PDQ, CAL, ECE,

DRST_SEL

0.69 x V_A

V (min)

V_IH

Logic High Input Voltage

Logic Low Input Voltage

0.79 x V_A

0.28 x V_A

0.21 x V_A

OutEdge, FSR, CalDly

V (min)

V (max)

OutV, DCLK_RST, PD, PDQ, CAL

OutEdge, FSR, CalDly, ECE, DRST_SEL

V_IL

Input Capacitance

(Note 11, Note 13)

C_IN

Each input to ground

1.2

pF

DIGITAL OUTPUT CHARACTERISTICS

mV_P-P(min)

mV_P-P(max)

mV_P-P(min)

mV_P-P(max)

Measured differentially, OutV = V_A,

460

975

300

740

660

580

±1

V_BG= Floating (Note 15)

LVDS Differential Output

Voltage

V_OD

Measured differentially, OutV = GND, V_BG

= Floating (Note 15)

Change in LVDS Output Swing

ΔV_{O DIFF}

mV

Between Logic Levels

V_BG= Floating

800

mV

Output Offset Voltage

See Figure 1

V_OS

V_BG= V_A(Note 15)

1175

Output Offset Voltage Change

Between Logic Levels

ΔV_OS

±1

±4

mV

mA

Output+ and Output−

connected to 0.8V

I_OS

Output Short Circuit Current

Z_O

Differential Output Impedance

CalRun H level output

100

1.65

0.15

Ohms

V_OH

V_OL

I_OH= −400 µA (Note 12)

I_OH= 400 µA (Note 12)

1.5

0.3

V

CalRun L level output

POWER SUPPLY CHARACTERISTICS (NON-DES MODE)

1:2 Demux Mode; f_CLK= 1.5 GHz

ꢀ

PD = PDQ = Low

PD = Low, PDQ = High

PD = PDQ = High

810

560

1.3

930

630

mA (max)

mA

I_A

Analog Supply Current

Output Driver Supply Current

Power Consumption

1:2 Demux Mode; f_CLK= 1.5 GHz

PD = PDQ = Low

PD = Low, PDQ = High

PD = PDQ = High

ꢀ

190

107

ꢀ

295

163

ꢀ

mA (max)

mA

I_DR

0.025

1:2 Demux Mode; f_CLK= 1.5 GHz

PD = PDQ = Low

PD = Low, PDQ = High

PD = PDQ = High

ꢀ

1.9

1.25

2.5

ꢀ

2.33

1.53

ꢀ

W (max)

mW

P_D

Change in Full Scale Error with change in

V_Afrom 1.8V to 2.0V

D.C. Power Supply Rejection

Ratio

PSRR1

-30

dB

12

ADC07D1520

Typical

(Note 8)

Units

(Limits)

Symbol

Parameter

Conditions

Limits

1.5

A.C. ELECTRICAL CHARACTERISTICS

Maximum Input Clock

Frequency

f_{CLK (max)}

Demux Mode (DES or Non-DES Mode)

GHz

1:2 Demux Non-DES Mode

1:4 Demux DES Mode

200

500

20

MHz

Minimum Input Clock

Frequency

f_{CLK (min)}

% (min)

% (max)

ps (min)

f_CLK(min)≤ f_CLK≤ 1.5 GHz

(Note 12)

Input Clock Duty Cycle

50

80

t_CL

t_CH

Input Clock Low Time

Input Clock High Time

(Note 11)

333

133

45

ps (min)

% (min)

% (max)

ps

DCLK Duty Cycle

(Note 11)

50

55

t_SR

t_HR

Setup Time DCLK_RST±

Hold Time DCLK_RST±

(Note 12)

90

30

ps

Input Clock

Cycles (min)

t_PWR

t_LHT

t_HLT

Pulse Width DCLK_RST±

(Note 11)

4

Differential Low-to-High

Transition Time

10% to 90%, C_L= 2.5 pF

150

ps

Differential High-to-Low

Transition Time

50% of DCLK transition to 50% of Data

transition, SDR Mode

t_OSK

DCLK-to-Data Output Skew

±50

ps (max)

and DDR Mode, 0° DCLK (Note 11)

t_SU

t_H

t_AD

t_AJ

Data-to-DCLK Set-Up Time

DCLK-to-Data Hold Time

Sampling (Aperture) Delay

Aperture Jitter

DDR Mode, 90° DCLK (Note 11)

Input CLK+ Fall to Acquisition of Data

400

560

1.6

0.4

ps

ns

ps (rms)

Input Clock-to Data Output

Delay (in addition to Pipeline

Delay)

50% of Input Clock transition to 50% of Data

transition

t_OD

4.0

ns

DI Outputs

13

14

DId Outputs

Pipeline Delay (Latency) in 1:2

Demux Mode

(Note 11, Note 14)

Non-DES Mode

DQ Outputs

13

Input Clock

Cycles

DES Mode

13.5

14

Non-DES Mode

DQd Outputs

DES Mode

14.5

13

DI Outputs

Pipeline Delay (Latency) in

Non-Demux Mode

(Note 11, Note 14)

Input Clock

Cycles

Non-DES Mode

DQ Outputs

13

DES Mode

13.5

Differential V_INstep from ±1.2V to 0V to get

accurate conversion

Input Clock

Cycle

Over Range Recovery Time

1

PD low to Rated Accuracy

Conversion (Wake-Up Time)

Non-DES Mode (Note 11)

DES Mode (Note 11)

500

1

ns

µs

t_WU

f_SCLK

t_SSU

Serial Clock Frequency

(Note 11)

15

MHz

Serial Data to Serial Clock

Rising Setup Time

(Note 11)

2.5

1

ns (min)

ns

Serial Data to Serial Clock

Rising Hold Time

t_SH

(Note 11)

CS to Serial Clock Rising Setup

Time

t_SCS

2.5

13

ADC07D1520

Typical

(Note 8)

Units

(Limits)

Symbol

Parameter

Conditions

Limits

CS to Serial Clock Falling Hold

Time

t_HCS

1.5

ns

Serial Clock Low Time

Serial Clock High Time

Calibration Cycle Time

30

ns (min)

t_CAL

1.4 x 10⁶

Clock Cycles

(min)

t_{CAL_L}

CAL Pin Low Time

CAL Pin High Time

See Figure 10 (Note 11)

1280

Clock Cycles

(min)

t_{CAL_H}

See Figure 10 (Note 11)

CalDly = Low

See 1.1.1 Calibration, Figure 10,

(Note 11)

Clock Cycles

(max)

2²⁶

Calibration delay determined

by CalDly (pin 127)

t_CalDly

CalDly = High

See 1.1.1 Calibration, Figure 10,

(Note 11)

Clock Cycles

(max)

2³²

14

ADC07D1520

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. There is no guarantee of operation at the Absolute Maximum

Ratings. Operating Ratings indicate conditions for which the device is functional, but do not guarantee specific performance limits. For guaranteed specifications

and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics

may degrade when the device is not operated under the listed test conditions.

Note 2: All voltages are measured with respect to GND = DR GND = 0V, unless otherwise specified.

Note 3: When the input voltage at any pin exceeds the power supply limits (that is, less than GND or greater than V_A), the current at that pin should be limited to

25 mA. The 50 mA maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 25 mA to

two. This limit is not placed upon the power, ground and digital output pins.

Note 4: Human body model is 100 pF capacitor discharged through a 1.5 kΩ resistor. Machine model is 220 pF discharged through ZERO Ohms. Charged device

model simulates a pin slowly acquiring charge (such as from a device sliding down the feeder in an automated assembler) then rapidly being discharged.

Note 5: Reflow temperature profiles are different for lead-free and non-lead-free packages.

Note 6: The analog inputs are protected as shown below. Input voltage magnitudes beyond the Absolute Maximum Ratings may damage this device.

30194104

Note 7: To guarantee accuracy, it is required that V_Aand V_DRbe well bypassed. Each supply pin must be decoupled with separate bypass capacitors. Additionally,

achieving rated performance requires that the backside exposed pad be well grounded.

Note 8: Typical figures represent most likely parametric norms at T_A= 25°C and nominal supply voltages at the time of product characterization and are not

guaranteed.

Note 9: Calculation of Full-Scale Error for this device assumes that the actual reference voltage is exactly its nominal value. Full-Scale Error for this device,

therefore, is a combination of Full-Scale Error and Reference Voltage Error. See Figure 2. For relationship between Gain Error and Full-Scale Error, see

Specification Definitions for Gain Error.

Note 10: The analog and clock input capacitances are die capacitances only. Additional package capacitances of 0.65 pF differential and 0.95 pF each pin to

ground are isolated from the die capacitances by lead and bond wire inductances.

Note 11: This parameter is guaranteed by design and is not tested in production.

Note 12: This parameter is guaranteed by design and/or characterization and is not tested in production.

Note 13: The digital control pin capacitances are die capacitances only. Additional package capacitance of 1.6 pF each pin to ground are isolated from the die

capacitances by lead and bond wire inductances.

Note 14: The ADC07D1520 has two LVDS output buses, each of which clocks data out at one half the sample rate. The second bus (D0 through D6) has a

pipeline latency that is one clock cycle less than the latency of the first bus (Dd0 through Dd6).

Note 15: Tying V_BGto the supply rail will increase the output offset voltage (V_OS) by 400mv (typical), as shown in the V_OSspecification above. Tying V_BGto the

supply rail will also affect the differential LVDS output voltage (V_OD), causing it to increase by 40mV (typical).

Note 16: The maximum clock frequency for Non-Demux Mode is 1 GHz.

Note 17: This feature is not tested for performance or functionality in production.

Note 18: Production test coverage does not guarantee all possible combinations of Non-Extended and/or Extended mode device configuration settings.

15

ADC07D1520

Specification Definitions

APERTURE (SAMPLING) DELAY is the amount of delay, measured from the sampling edge of the CLK input, after which the

signal present at the input pin is sampled inside the device.

APERTURE JITTER (t_AJ) is the variation in aperture delay from sample to sample. Aperture jitter shows up as input noise.

CODE ERROR RATE (C.E.R.) is the probability of error and is defined as the probable number of word errors on the ADC output

per unit of time divided by the number of words seen in that amount of time. A C.E.R. of 10^-18corresponds to a statistical error in

one word about every four (4) years.

CLOCK DUTY CYCLE is the ratio of the time that the clock waveform is at a logic high to the total time of one clock period.

DIFFERENTIAL NON-LINEARITY (DNL) is the measure of the maximum deviation from the ideal step size of 1 LSB. Measured

at sample rate = 500 MSPS with a 1MHz input sine wave.

EFFECTIVE NUMBER OF BITS (ENOB, or EFFECTIVE BITS) is another method of specifying Signal-to-Noise and Distortion

Ratio, or SINAD. ENOB is defined as (SINAD − 1.76) / 6.02 and says that the converter is equivalent to a perfect ADC of this

(ENOB) number of bits.

FULL POWER BANDWIDTH (FPBW) is a measure of the frequency at which the reconstructed output fundamental drops 3 dB

below its low frequency value for a full-scale input.

GAIN ERROR is the deviation from the ideal slope of the transfer function. It can be calculated from Offset and Full-Scale Errors:

Positive Gain Error = Offset Error − Positive Full-Scale Error

Negative Gain Error = −(Offset Error − Negative Full-Scale Error)

Gain Error = Negative Full-Scale Error − Positive Full-Scale Error = Positive Gain Error + Negative Gain Error

INTEGRAL NON-LINEARITY (INL) is a measure of worst case deviation of the ADC transfer function from an ideal straight line

drawn through the ADC transfer function. The deviation of any given code from this straight line is measured from the center of

that code value step. The best fit method is used.

INTERMODULATION DISTORTION (IMD) is the creation of additional spectral components as a result of two sinusoidal frequen-

cies being applied to the ADC input at the same time. It is defined as the ratio of the power in the second and third order

intermodulation products to the power in one of the original frequencies. IMD is usually expressed in dBFS.

LSB (LEAST SIGNIFICANT BIT) is the bit that has the smallest value or weight of all bits. This value is

V_FS/ 2^N

where V_FSis the differential full-scale amplitude V_INas set by the FSR input and "N" is the ADC resolution in bits, which is 7 for the

ADC07D1520.

LOW VOLTAGE DIFFERENTIAL SIGNALING (LVDS) DIFFERENTIAL OUTPUT VOLTAGE (V_IDand V_OD) is two times the ab-

solute value of the difference between the V_D+ and V_D- signals; each measured with respect to Ground.

30194146

FIGURE 1. LVDS Output Signal Levels

LVDS OUTPUT OFFSET VOLTAGE (V_OS) is the midpoint between the D+ and D- pins output voltage with respect to ground; i.e.,

[(V_D+) +( V_D-)]/2. See Figure 1.

MISSING CODES are those output codes that are skipped and will never appear at the ADC outputs. These codes cannot be

reached with any input value.

MSB (MOST SIGNIFICANT BIT) is the bit that has the largest value or weight. Its value is one half of full scale.

NEGATIVE FULL-SCALE ERROR (NFSE) is a measure of how far the first code transition is from the ideal 1/2 LSB above a

differential −V_IN/2 with the FSR pin low. For the ADC07D1520 the reference voltage is assumed to be ideal, so this error is a

combination of full-scale error and reference voltage error.

OFFSET ERROR (V_OFF) is a measure of how far the mid-scale point is from the ideal zero voltage differential input.

Offset Error = Actual Input causing average of 8k samples to result in an average code of 127.5.

OUTPUT DELAY (t_OD) is the time delay (in addition to Pipeline Delay) after the falling edge of CLK+ before the data update is

present at the output pins.

OVER-RANGE RECOVERY TIME is the time required after the differential input voltages goes from ±1.2V to 0V for the converter

to recover and make a conversion with its rated accuracy.

16

ADC07D1520

PIPELINE DELAY (LATENCY) is the number of input clock cycles between initiation of conversion and when that data is presented

to the output driver stage. New data is available at every clock cycle, but the data lags the conversion by the Pipeline Delay plus

the t_OD

.

POSITIVE FULL-SCALE ERROR (PFSE) is a measure of how far the last code transition is from the ideal 1-1/2 LSB below a

differential +V_IN/2. For the ADC07D1520 the reference voltage is assumed to be ideal, so this error is a combination of full-scale

error and reference voltage error.

POWER SUPPLY REJECTION RATIO (PSRR) can be one of two specifications. PSRR1 (D.C. PSRR) is the ratio of the change

in full-scale error that results from a power supply voltage change from 1.8V to 2.0V. PSRR2 (A.C. PSRR) is a measure of how

well an a.c. signal riding upon the power supply is rejected from the output and is measured with a 248 MHz, 50 mV_P-Psignal riding

upon the power supply. It is the ratio of the output amplitude of that signal at the output to its amplitude on the power supply pin.

PSRR is expressed in dB.

SIGNAL TO NOISE RATIO (SNR) is the ratio, expressed in dB, of the rms value of the input signal at the output to the rms value

of the sum of all other spectral components below one-half the sampling frequency, not including harmonics or d.c.

SIGNAL TO NOISE PLUS DISTORTION (S/(N+D) or SINAD) is the ratio, expressed in dB, of the rms value of the input signal at

the output to the rms value of all of the other spectral components below half the input clock frequency, including harmonics but

excluding d.c.

SPURIOUS-FREE DYNAMIC RANGE (SFDR) is the difference, expressed in dB, between the rms values of the input signal at

the output and the peak spurious signal, where a spurious signal is any signal present in the output spectrum that is not present

at the input, excluding d.c.

TOTAL HARMONIC DISTORTION (THD) is the ratio expressed in dB, of the rms total of the first nine harmonic levels at the output

to the level of the fundamental at the output. THD is calculated as

where A_f1is the RMS power of the fundamental (output) frequency and A_f2through A_f10are the RMS power of the first 9 harmonic

frequencies in the output spectrum.

– Second Harmonic Distortion (2nd Harm) is the difference, expressed in dB, between the RMS power in the input frequency

seen at the output and the power in its 2nd harmonic level at the output.

– Third Harmonic Distortion (3rd Harm) is the difference expressed in dB between the RMS power in the input frequency seen

at the output and the power in its 3rd harmonic level at the output.

17

ADC07D1520

Transfer Characteristic

30194122

FIGURE 2. Input / Output Transfer Characteristic

18

ADC07D1520

Timing Diagrams

30194114

FIGURE 3. SDR Clocking in 1:2 Demultiplexed Non-DES Mode

30194159

FIGURE 4. DDR Clocking in 1:2 Demultiplexed Non-DES Mode

19

ADC07D1520

30194160

FIGURE 5. DDR Clocking in Non-Demultiplexed Non-DES Mode

30194119

FIGURE 6. Serial Interface Timing

30194120

FIGURE 7. Clock Reset Timing in DDR Mode

20

ADC07D1520

30194123

FIGURE 8. Clock Reset Timing in SDR Mode with OUTEDGE Low

30194124

FIGURE 9. Clock Reset Timing in SDR Mode with OUTEDGE High

30194125

FIGURE 10. Power-on and On-Command Calibration Timing

21

ADC07D1520

Typical Performance Characteristics V_A= V_DR= 1.9V, f_CLK= 1500 MHz, f_IN= 748 MHz, T_A= 25°C, I

channel, 1:2 Demux Mode (1:1 Demux Mode has similar performance), unless otherwise stated.

POWER CONSUMPTION vs. CLOCK FREQUENCY

ENOB vs. TEMPERATURE

2.5

7.0

6.9

6.8

6.7

2.0

1.5

1.0

0

500

1000

1500

-50

0

50

100

CLOCK FREQUENCY (MHz)

TEMPERATURE (°C)

30194181

30194196

ENOB vs. SUPPLY VOLTAGE

ENOB vs. CLOCK FREQUENCY

7.0

6.9

6.8

6.7

7.0

6.9

6.8

6.7

I Channel

Q Channel

I-Channel

Q-Channel

1.80

1.85

1.90

(V)

1.95

2.00

0

500

1000

1500

V

CLOCK FREQUENCY (MHz)

A

30194177

30194178

ENOB vs. INPUT FREQUENCY

SNR vs. TEMPERATURE

7.0

6.8

6.6

6.4

6.2

6.0

45

44

43

42

41

I-Channel

Q-Channel

0

500

1000

1500

-50

0

50

100

INPUT FREQUENCY (MHz)

TEMPERATURE (°C)

30194179

30194168

22

ADC07D1520

SNR vs. SUPPLY VOLTAGE

SNR vs. CLOCK FREQUENCY

45

44

43

42

41

45

44

43

42

41

I-Channel

Q-Channel

I-Channel

Q-Channel

1.80

1.85

1.90

(V)

1.95

2.00

0

500

1000

1500

V

CLOCK FREQUENCY (MHz)

A

30194169

30194170

SNR vs. INPUT FREQUENCY

THD vs. TEMPERATURE

45

44

43

42

41

-40

-45

-50

-55

-60

I-Channel

Q-Channel

0

500

1000

1500

-50

0

50

100

INPUT FREQUENCY (MHz)

TEMPERATURE (°C)

30194171

30194172

THD vs. SUPPLY VOLTAGE

THD vs. CLOCK FREQUENCY

-40

-45

-50

-55

-60

-40

-45

-50

-55

-60

I-Channel

Q-Channel

I-Channel

Q-Channel

1.80

1.85

1.90

(V)

1.95

2.00

0

500

1000

1500

V

CLOCK FREQUENCY (MHz)

A

30194173

30194174

23

ADC07D1520

THD vs. INPUT FREQUENCY

SFDR vs. TEMPERATURE

-40

-45

-50

-55

-60

65

60

55

50

45

I-Channel

Q-Channel

0

500

1000

1500

-50

0

50

100

INPUT FREQUENCY (MHz)

TEMPERATURE (°C)

30194175

30194185

SFDR vs. SUPPLY VOLTAGE

SFDR vs. CLOCK FREQUENCY

65

60

55

50

45

65

60

55

50

45

I-Channel

Q-Channel

I-Channel

Q-Channel

1.80

1.85

1.90

(V)

1.95

2.00

0

500

1000

1500

V

CLOCK FREQUENCY (MHz)

A

30194184

30194182

SFDR vs. INPUT FREQUENCY

Spectral Response at FIN = 373 MHz

65

60

55

50

45

0

I-Channel

Q-Channel

-10

-20

-30

-40

-50

-60

-70

-80

0

500

1000

1500

0

250

500

750

INPUT FREQUENCY (MHz)

FREQUENCY (MHz)

30194183

30194187

24

ADC07D1520

Spectral Response at FIN = 748 MHz

CROSSTALK vs. SOURCE FREQUENCY

0

-10

-20

-30

-40

-50

-60

-70

-80

0

250

500

750

FREQUENCY (MHz)

30194188

30194163

FULL POWER BANDWIDTH (NON-DES MODE)

GAIN STABILITY vs. DIE TEMPERATURE

30194186

30194195

25

ADC07D1520

1.0 Functional Description

The ADC07D1520 is a versatile A/D Converter with an innovative architecture permitting very high speed operation. The controls

available ease the application of the device to circuit solutions. Optimum performance requires adherence to the provisions dis-

cussed here and in the Applications Information Section.

While it is generally poor practice to allow an active pin to float, pins 4, 14, 52 and 127 of the ADC07D1520 are designed to be left

floating without jeopardy. In all discussions for pins 4, 14, and 127, whenever a function is called by allowing these control pins to

float, connecting that pin to a potential of one half the V_Asupply voltage will have the same effect as allowing it to float.

1.1 OVERVIEW

The ADC07D1520 uses a calibrated folding and interpolating architecture that achieves 6.8 effective bits. The use of folding am-

plifiers greatly reduces the number of comparators and power consumption. Interpolation reduces the number of front-end amplifiers

required, minimizing the load on the input signal and further reducing power requirements. In addition to correcting other non-

idealities, on-chip calibration reduces the INL bow often seen with folding architectures. The result is an extremely fast, high

performance, low power converter.

The analog input signal that is within the converter's input voltage range is digitized to seven bits at speeds of 200 MSPS to 1.5

GSPS. Differential input voltages below negative full-scale will cause the output word to consist of all zeroes. Differential input

voltages above positive full-scale will cause the output word to consist of all ones. Either of these conditions at either the I- or Q-

channel will cause the Out of Range (OR) output to be activated. This single OR output indicates when the output code from one

or both of the channels is below negative full scale or above positive full scale. When PDQ is asserted, the OR indication applies

to the I channel only.

For Non-DES Modes, each converter has a selectable output demultiplexer which feeds two LVDS buses. If the 1:2 Demux Mode

is selected, the output data rate is reduced to half the input sample rate on each bus. When Non-demux Mode is selected, the

output data rate on channels DI and DQ are at the same rate as the input sample clock.

The output levels may be selected to be normal or reduced. Using reduced levels saves power but could result in erroneous data

capture of some or all of the bits, especially at higher sample rates and in marginally designed systems.

1.1.1 Calibration

A calibration is performed upon power-up and can also be invoked by the user upon command. Calibration trims the 100Ω analog

input differential termination resistor and minimizes full-scale error, offset error, DNL and INL, resulting in maximizing SNR, THD,

SINAD (SNDR) and ENOB. Internal bias currents are also set during the calibration process. All of this is true whether the calibration

is performed upon power up or is performed upon command. Running the calibration is required for proper operation and to obtain

the ADC's specified performance. In addition to the requirement to be run at power-up, an on-command calibration must be run

whenever the sense of the FSR pin is changed. For best performance, it is recommend that an on-command calibration be run 20

seconds or more after application of power and whenever the operating temperature changes significantly, relative to the specific

system performance requirements. See 2.4.2.2 On-Command Calibration for more information. Calibration cannot be initiated or

run while the device is in the power-down mode. See 1.1.7 Power Down for information on the interaction between Power Down

and Calibration.

In normal operation, calibration is performed just after application of power and whenever a valid calibration command is given,

which may be accomplished one of two ways, via the CAL pin (30) or the Calibration register (Addr: 0h, Bit 15). The calibration

command is achieved by holding the CAL pin low for at least t_{CAL_L}clock cycles, and then holding it high for at least another

t_{CAL_H}clock cycles, as defined in the Converter Electrical Characteristics. The time taken by the calibration procedure is specified

as t_CALin Converter Electrical Characteristics. Holding the CAL pin high upon power up will prevent the calibration process from

running until the CAL pin experiences the above-mentioned t_{CAL_L}clock cycles followed by t_{CAL_H}clock cycles.

CalDly (pin 127) is used to select one of two delay times that take place from the application of power to the start of calibration.

This calibration delay time is dependent on the setting of the CalDly pin and is specified as t_CalDlyin the Converter Electrical

Characteristics. These delay values allow the power supply to come up and stabilize before calibration takes place. If the PD pin

is high upon power-up, the calibration delay counter will be disabled until the PD pin is brought low. Therefore, holding the PD pin

high during power up will further delay the start of the power-up calibration cycle. The best setting of the CalDly pin depends upon

the power-on settling time of the power supply.

1.1.2 Acquiring the Input

In 1:2 Demux Non-DES Mode, data is acquired at the falling edge of CLK+ (pin 18) and the digital equivalent of that data is available

at the digital outputs 13 input clock cycles later for the DI and DQ output buses and 14 input clock cycles later for the DId and DQd

output buses. See Pipeline Delay in the Converter Electrical Characteristics. There is an additional internal delay called t_ODbefore

the data is available at the outputs. See the Timing Diagrams. The ADC07D1520 will convert as long as the input clock signal is

present. The fully differential comparator design and the innovative design of the sample-and-hold amplifier, together with self

calibration, enables a very flat SINAD/ENOB response beyond 1.5 GHz. The ADC07D1520 output data signaling is LVDS and the

output format is offset binary.

1.1.3 Control Modes

Much of the user control can be accomplished with several control pins that are provided. Examples include initiation of the cali-

bration cycle, power down mode and full scale range setting. However, the ADC07D1520 also provides an Extended Control Mode

whereby a serial interface is used to access register-based control of several advanced features. The Extended Control Mode is

not intended to be enabled and disabled dynamically. Rather, the user is expected to employ either the Non-extended Control

Mode or the Extended Control Mode at all times. When the device is in the Extended Control Mode, pin-based control of several

26

ADC07D1520

features is replaced with register-based control and those pin-based controls are disabled. These pins are OutV (pin 3), OutEdge/

DDR (pin 4), FSR (pin 14) and CalDly/DES (pin 127). See 1.2 NON-EXTENDED AND EXTENDED CONTROL MODE for details

on the Extended Control Mode.

1.1.4 The Analog Inputs

The ADC07D1520 must be driven with a differential input signal. Operation with a single-ended signal is not recommended. It is

important that the inputs either be a.c. coupled to the inputs with the V_CMO(pin 7) grounded, or d.c. coupled with the V_CMOpin left

floating. An input common mode voltage equal to the V_CMOoutput must be provided as the common mode input voltage to V_IN+

and V_IN- when d.c. coupling is used.

Two full-scale range settings are provided via pin 14 (FSR). In Non-extended Control Mode, a logic high on pin 14 causes an input

full-scale range setting of a normal V_INinput level, while a logic low on pin 14 causes an input full-scale range setting of a reduced

V_INinput level. The full-scale range setting operates on both ADCs.

In the Extended Control Mode, programming the Input Full-Scale Voltage Adjust register allows the input full-scale range to be

adjusted as described in 1.4 REGISTER DESCRIPTION and 2.2 THE ANALOG INPUT.

1.1.5 Clocking

The ADC07D1520 must be driven with an a.c. coupled, differential clock signal. 2.3 THE CLOCK INPUTS describes the use of the

clock input pins. A differential LVDS output clock is available for use in latching the ADC output data into whatever device is used

to receive the data.

The ADC07D1520 offers output clocking options: two of these options are Single Data Rate (SDR) and Double Data Rate (DDR).

In SDR mode, the user has a choice of which Data Clock (DCLK) edge, rising or falling, the output data transitions on.

The ADC07D1520 also has the option to use a duty cycle corrected clock receiver as part of the input clock circuit. This feature is

enabled by default and provides improved ADC clocking, especially in the Dual-Edge Sampling (DES) Mode. This circuitry allows

the ADC to be clocked with a signal source having a duty cycle ratio of 20%/80% (worst case) for both the Non-DES and the DES

Modes.

1.1.5.1 Dual-Edge Sampling

The Dual-Edge Sampling (DES) Mode allows either of the ADC07D1520's inputs (I- or Q-channel) to be sampled by both ADCs.

One ADC samples the input on the rising edge of the input clock and the other ADC samples the same input on the falling edge of

the input clock. A single input is thus sampled twice per input clock cycle, resulting in an overall sample rate of twice the input clock

frequency, or 3 GSPS with a 1.5 GHz input clock.

In this mode, the outputs must be carefully interleaved to reconstruct the sampled signal. If the device is programmed into the 1:4

Demux DES Mode, the data is effectively demultiplexed by 1:4. If the input clock is 1.5 GHz, the effective sampling rate is doubled

to 3 GSPS and each of the 4 output buses has an output rate of 750 MHz. All data is available in parallel. To properly reconstruct

the sampled waveform, the four bytes of parallel data that are output with each clock are in the following sampling order, from the

earliest to the latest, and must be interleaved as such: DQd, DId, DQ, DI. Table 1 indicates what the outputs represent for the

various sampling possibilities. If the device is programmed into the Non-demux DES Mode, two bytes of parallel data are output

with each edge of the clock in the following sampling order, from the earliest to the latest: DQ, DI. See Table 2.

In the Non-extended Control and DES Mode of operation, only the I-channel can be sampled. In the Extended Control Mode of

operation, the user can select which input is sampled.

The ADC07D1520 also includes an automatic clock phase background adjustment in DES Mode to automatically and continuously

adjust the clock phase of the I- and Q-channels. This feature removes the need to adjust the clock phase setting manually and

provides optimal DES Mode performance.

TABLE 1. Input Channel Samples Produced at Data Outputs in 1:2 Demultiplexed Mode**

Data Outputs

(Always sourced with

respect to fall of DCLK+)

Dual-Edge Sampling (DES) Mode

I-Channel Selected Q-Channel Selected *

I-channel sampled with fall Q-channel sampled with fall

Non-DES Sampling Mode

I-channel sampled with fall of CLK,

13 cycles earlier.

DI

DId

DQ

of CLK,

13 cycles earlier.

I-channel sampled with fall Q-channel sampled with fall

I-channel sampled with fall of CLK,

14 cycles earlier.

of CLK,

14 cycles earlier.

I-channel sampled with rise Q-channel sampled with rise

Q-channel sampled with fall of CLK,

13 cycles earlier.

of CLK,

13.5 cycles earlier.

I-channel sampled with rise Q-channel sampled with rise

Q-channel sampled with fall of CLK,

14 cycles earlier.

DQd

of CLK,

14.5 cycles earlier.

* Note that, in DES Mode and Non-extended Control Mode, only the I-channel is sampled. In DES Mode and Extended Control Mode, the I- or Q-channel can be

sampled.

** Note that, in the Non-demux Mode (DES and Non-DES Mode), the DId and DQd outputs are disabled and are high impedance.

27

ADC07D1520

TABLE 2. Input Channel Samples Produced at Data Outputs in Non-Demux Mode

Data Outputs Dual-Edge Sampling (DES) Mode

(Always sourced with

respect to fall of DCLK+)

Non-DES Sampling Mode

I-Channel Selected Q-Channel Selected

I-channel sampled with fall Q-channel sampled with fall

I-channel sampled with fall of CLK,

14 cycles earlier.

DI

of CLK,

14 cycles earlier.

13.5 cycles earlier.

No output;

high impedance.

No output;

high impedance.

No output;

high impedance.

DId

DQ

I-channel sampled with rise Q-channel sampled with rise

of CLK,

13.5 cycles earlier.

Q-channel sampled with fall of CLK,

13.5 cycles earlier.

of CLK,

13.5 cycles earlier.

No output;

high impedance.

No output;

high impedance.

No output;

high impedance.

DQd

1.1.5.2 OutEdge and Demultiplex Control Setting

To help ease data capture in the Single Data Rate (SDR) mode, the output data may be caused to transition on either the positive

or the negative edge of the output data clock (DCLK). In the Non-extended Control Mode, this is selected by OutEdge (pin 4). A

logic high on the OutEdge input pin causes the output data to transition on the rising edge of DCLK+, while a logic low causes the

output to transition on the falling edge of DCLK+. See 2.4.3 Output Edge Synchronization. When in the Extended Control Mode,

the OutEdge is selected using the OED bit in the Configuration Register. This bit has two functions. In the SDR mode, the bit

functions as OutEdge and selects the DCLK edge with which the data transitions. In the Double Data Rate (DDR) mode, this bit

selects whether the device is in Non-demux or Demux Mode. In the DDR case, the DCLK has a 0° phase relationship with the

output data, independent of the demultiplexer selection. For 1:2 Demux DDR 0° Mode, there are four, as opposed to three cycles

of CLK delay from the deassertion of DCLK_RST to the Synchronizing Edge. See 1.5 MULTIPLE ADC SYNCHRONIZATION for

more information.

1.1.5.3 Double Data Rate and Single Data Rate

A choice of Single Data Rate (SDR) or Double Data Rate (DDR) output is offered. With SDR, the output clock (DCLK) frequency

is the same as the data rate of the two output buses. With DDR, the DCLK frequency is half the data rate and data is sent to the

outputs on both edges of DCLK. DDR clocking is enabled in Non-extended Control Mode by allowing pin 4 to float or by biasing it

to half the supply.

1.1.5.4 Clocking Summary

The chip may be in one of four modes, depending on the Dual-Edge Sampling (DES) selection and the demultiplex selection. For

the DES selection, there are two possibilities: Non-DES Mode and DES Mode. In Non-DES Mode, each of the channels (I-channel

and Q-channel) functions independently, i.e. the chip is a dual 1.5 GSPS A/D converter. In DES Mode, the I- and Q-channels are

interleaved and function together as one 3.0 GSPS A/D converter. For the demultiplex selection, there are also two possibilities:

Demux Mode and Non-Demux Mode. The I-channel has two 7-bit output busses associated with it: DI and DId. The Q-channel

also has two 7-bit output busses associated with it: DQ and DQd. In Demux Mode, the channel is demultiplexed by 1:2. In Non-

Demux Mode, the channel is not demultiplexed. Note that Non-Demux Mode is also sometimes referred to as 1:1 Demux Mode.

For example, if the I-channel was in Non-Demux Mode, the corresponding digital output data would be available on only the DI

bus. If the I-channel was in Demux Mode, the corresponding digital output data would be available on both the DI and DId busses,

but at half the rate of Non-Demux Mode.

Given that there are two DES Mode selections (DES Mode and Non-DES Mode) and two demultiplex selections (Demux Mode

and Non-Demux Mode), this yields a total of four possible modes: (1) Non-Demux Non-DES Mode, (2) Non-Demux DES Mode,

(3) 1:2 Demux Non-DES Mode, and (4) 1:4 Demux DES Mode. The following is a brief explanation of the terms and modes:

1. Non-Demux Non-DES Mode: This mode is when the chip is in Non-Demux Mode and Non-DES Mode. The I- and Q- channels

function independently of one another. The digital output data is available for the I-channel on DI, and for the Q-channel on

DQ.

2. Non-Demux DES Mode: This mode is when the chip is in Non-Demux Mode and DES Mode. The I- and Q- channels are

interleaved and function together as one channel. The digital output data is available on the DI and DQ busses because

although the chip is in Non-Demux Mode, both I- and Q-channels are functioning and passing data.

3. 1:2 Demux Non-DES Mode: This mode is when the chip is in Demux Mode and Non-DES Mode. The I- and Q- channels

function independently of one another. The digital output data is available for the I-channel on DI and DId, and for the Q-channel

on DQ and DQd. This is because each channel (I-channel and Q-channel) is providing digital data in a demultiplexed manner.

4. 1:4 Demux DES Mode: This mode is when the chip is in Demux Mode and DES Mode. The I- and Q- channels are interleaved

and function together as one channel. The digital output data is available on the DI, DId, DQ and DQd busses because although

the chip is in Demux Mode, both I- and Q-channels are functioning and passing data. To avoid confusion, this mode is labeled

1:4 because the analog input signal is provided on one channel and the digital output data is provided on four busses.

The choice of Dual Data Rate (DDR) and Single Data Rate (SDR) will only affect the speed of the output Data Clock (DCLK). Once

the DES Modes and Demux Modes have been chosen, the data output rate is also fixed. In the case of SDR, the DCLK runs at

28

ADC07D1520

the same rate as the output data; output data may transition with either the rising or falling edge of DCLK. In the case of DDR, the

DCLK runs at half the rate of the output data; the output data transitions on both rising and falling edges of the DCLK.

1.1.6 The LVDS Outputs

The Data, Out Of Range (OR+/-), and Data Clock (DCLK+/-) outputs are LVDS. The electrical specifications of the LVDS outputs

are compatible with typical LVDS receivers available on ASIC and FPGA chips; but they are not IEEE or ANSI communications

standards compliant due to the low +1.9V supply used on this chip. The user is given the choice of a lower signal amplitude via the

OutV control pin or the OV control register bit. For short LVDS lines and low noise systems, satisfactory performance may be

realized with the OutV input low, which results in lower power consumption. If the LVDS lines are long and/or the system in which

the ADC07D1520 is used is noisy, it may be necessary to tie the OutV pin high.

The LVDS data outputs have a typical common mode voltage of 800 mV when the V_BGpin is unconnected and floating. If a higher

common mode is required, this common mode voltage can be increased to 1175 mV by tying the V_BGpin to V_A.

IMPORTANT NOTE: Tying the V_BGpin to V_Awill also increase the differential LVDS output voltage by up to 40mV.

1.1.7 Power Down

The ADC07D1520 is in the active state when the Power Down pin (PD) is low. When the PD pin is high, the device is in the power

down mode. In this mode, the data output pins (both positive and negative) are put into a high impedance state and the device's

power consumption is reduced to a minimal level.

A logic high on the Power Down Q-channel (PDQ) pin will power down the Q-channel and leave the I-channel active. There is no

provision to power down the I-channel independently of the Q-channel. Upon return to normal operation, the pipeline will contain

meaningless information.

If the PD input is brought high while a calibration is running, the device will not go into power down until the calibration sequence

is complete. However, if power is applied and PD is already high, the device will not begin the calibration sequence until PD is

brought low. If a manual calibration is requested while the device is powered down, the calibration will not take place at all. That

is, the manual calibration input is completely ignored in the power down state. Calibration will function with the Q-channel powered

down, but that channel will not be calibrated if PDQ is high. If the Q-channel is subsequently to be used, it is necessary to perform

a calibration after PDQ is brought low.

1.2 NON-EXTENDED AND EXTENDED CONTROL MODE

Note: Production test coverage does not guarantee all possible combinations of Non-Extended and/or Extended mode device

configuration settings.

The ADC07D1520 may be operated in one of two control modes: Non-extended Control Mode or Extended Control Mode. In the

simpler Non-extended Control Mode, the user affects available configuration and control of the device through several control pins.

The Extended Control Mode provides additional configuration and control options through a serial interface and a set of 9 registers.

Extended Control Mode is selected by setting pin 41 to logic low. If pin 41 is floating and pin 52 is floating or logic high, pin 14 can

alternately be used to enable the Extended Control Mode. The choice of control modes is required to be a fixed selection and is

not intended to be switched dynamically while the device is operational.

Table 3 shows how several of the device features are affected by the control mode chosen.

TABLE 3. Features and Modes

Feature

Non-Extended Control Mode

Selected with pin 4

Extended Control Mode

Selected with nDE in the Configuration

Register (Addr-1h; bit-10).

SDR or DDR Clocking

Selected with DCP in the Configuration

Register (Addr-1h; bit-11).

DDR Clock Phase

Not Selectable (0° Phase Only)

SDR Data transitions with rising edge of

DCLK+ when pin 4 is logic high and on

falling edge when low.

SDR Data transitions with rising or

falling DCLK edge

Selected with OED in the Configuration

Register (Addr-1h; bit-8).

Normal differential data and DCLK

amplitude selected when pin 3 is logic

high and reduced amplitude selected

when low.

Selected with OV in the Configuration

Register (Addr-1h; bit-9).

LVDS output level

Short delay selected when pin 127 is logic

low and longer delay selected when high.

Power-On Calibration Delay

Short delay only.

Up to 512 step adjustments over a

nominal range specified in 1.4

REGISTER DESCRIPTION. Separate

Normal input full-scale range selected

when pin 14 is logic high and reduced

Full-Scale Range

range when low. Selected range applies range selected for I- and Q-channels.

to both channels.

Selected using Full Range Registers

(Addr-3h and Bh; bit-7 through 15).

29

ADC07D1520

512 steps of adjustment using the Input

Offset register specified in 1.4

Input Offset Adjust

Not possible

REGISTER DESCRIPTION for each

channel using Input Offset Registers

(Addr-2h and Ah; bit-7 thru 15).

Enabled by programming DEN in the

Extended Configuration Register

(Addr-9h; bit-13).

Enabled with pin 127 floating or tied to half

the supply

Dual Edge Sampling Selection

Dual Edge Sampling Input Channel

Selection

Either I- or Q-channel input may be

sampled by both ADCs.

Only I-channel Input can be used

Not possible

A test pattern can be made present at

the data outputs by setting TPO to 1b in

Extended Configuration Register

(Addr-9h; bit-15).

Test Pattern

The DCLK outputs will continuously be

present when RTD is set to 1b in

Extended Configuration Register

(Addr-9h; bit-14 to 7).

Resistor Trim Disable

Not possible

If the device is set in DDR, the output can

be programmed to be non-

demultiplexed. When OED in

Configuration Register is set 1b

(Addr-1h; bit-8), this selects non-

demultiplex. If OED is set 0b, this selects

1:2 demultiplex.

Selectable Output Demultiplexer

The OR outputs can be programmed to

become a second DCLK output when

nSD is set 0b in Configuration Register

(Addr-1h; bit-13).

Second DCLK Output

Not possible

The sampling clock phase can be

manually adjusted through the Coarse

and Intermediate Register (Addr-Fh;

bit-15 to 7) and Fine Register (Addr-Eh;

bit-15 to 8).

Sampling Clock Phase Adjust

The default state of the Extended Control Mode is set upon power-on reset (internally performed by the device) and is shown in

Table 4.

TABLE 4. Extended Control Mode Operation

(Pin 41 Logic Low or Pin 52 Logic High or Floating and Pin 14 Floating or V_A/2)

Feature

Extended Control Mode Default State

DDR Clocking

SDR or DDR Clocking

DDR Clock Phase

Data changes with DCLK edge (0° phase)

Normal amplitude

(See V_ODin Converter Electrical Characteristics)

LVDS Output Amplitude

Calibration Delay

Short Delay

(See t_CalDlyin Converter Electrical Characteristics)

Normal range for both channels

(See V_INin Converter Electrical Characteristics)

Full-Scale Range

Input Offset Adjust

Dual Edge Sampling (DES)

Test Pattern

No adjustment for either channel

Not enabled

Not present at output

Resistor Trim Disable

Trim enabled, DCLK not continuously present at output

1:2 Demultiplex

Selectable Output Demultiplexer

Second DCLK Output

Not present, pin 79 and 80 function as OR+ and OR-, respectively

No adjustment for fine, intermediate or coarse

Sampling Clock Phase Adjust

30

ADC07D1520

1.3 THE SERIAL INTERFACE

IMPORTANT NOTE: During the initial write using the serial interface, all nine registers must be written with desired or default

values. Subsequent writes to single registers are allowed.

Note: Production test coverage does not guarantee all possible combinations of Non-Extended and/or Extended mode device

configuration settings.

The 3-pin serial interface is enabled only when the device is in the Extended Control Mode. The pins of this interface are Serial

Clock (SCLK), Serial Data (SDATA) and Serial Interface Chip Select (SCS). Nine write only registers are accessible through this

serial interface.

SCS: This signal should be asserted low while accessing a register through the serial interface. Setup and hold times with respect

to the SCLK must be observed.

SCLK: Serial data input is accepted at the rising edge of this signal. There is no minimum frequency requirement for SCLK.

SDATA: Each register access requires a specific 32-bit pattern at this input. This pattern consists of a header, register address

and register value. The data is shifted in MSB first. Setup and hold times with respect to the SCLK must be observed.

Each Register access consists of 32 bits, as shown in Figure 6 of the Timing Diagrams. The fixed header pattern is 0000 0000

0001 (eleven zeros followed by a 1). The loading sequence is such that a "0" is loaded first. These 12 bits form the header. The

next 4 bits are the address of the register that is to be written to and the last 16 bits are the data written to the addressed register.

The addresses of the various registers are indicated in Table 5.

Refer to 1.4 REGISTER DESCRIPTION for information on the data to be written to the registers.

Subsequent register accesses may be performed immediately, starting with the 33rd SCLK. This means that the SCS input does

not have to be de-asserted and asserted again between register addresses. It is possible, although not recommended, to keep the

SCS input permanently enabled (logic low) when using Extended Control Mode.

Control register contents are retained when the device is put into power-down mode.

IMPORTANT NOTE: Do not write to the Serial Interface when calibrating the ADC. Doing so will impair the performance of the

device until it is re-calibrated correctly. Programming the serial registers will also reduce dynamic performance of the ADC for the

duration of the register access time.

TABLE 5. Register Addresses

4-Bit Address

Loading Sequence:

A3 loaded after Fixed Header pattern, A0 loaded last

A3 A2 A1 A0 Hex

Register Addressed

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0h

1h

2h

3h

4h

5h

6h

7h

8h

9h

Ah

Bh

Ch

Dh

Eh

Fh

Calibration

Configuration

I-channel Offset

I-channel Full-Scale Voltage Adjust

Reserved

Extended Configuration

Q-channel Offset

Q-channel Full-Scale Voltage Adjust

Reserved

Sampling Clock Phase Fine Adjust

Sample Clock Phase Intermediate and Coarse Adjust

31

ADC07D1520

1.4 REGISTER DESCRIPTION

Nine write-only registers provide several control and configuration options in the Extended Control Mode. These registers have no

effect when the device is in the Non-extended Control Mode. Each register description below also shows the Power-On Reset

(POR) state of each control bit.

Calibration Register

Addr: 0h (0000b)

Write only (0x7FFF)

D15 D14 D13 D12 D11 D10

D9

1

D8

1

D7

1

D6

1

D5

1

D4

1

D3

1

D2

1

D1

1

D0

1

CAL

1

Bit 15

CAL: Calibration Enable. When this bit is set 1b, an on-command calibration cycle is initiated. This function

is exactly the same as issuing an on-command calibration using the CAL pin. This bit is OR'd with the

CAL pin (30).

POR State: 0b

Bits 14:0 Must be set to 1b

Configuration Register

Addr: 1h (0001b)

Write only (0xB2FF)

D15 D14 D13 D12 D11 D10

D9

D8

D7

1

D6

1

D5

1

D4

1

D3

1

D2

1

D1

1

D0

1

0

nSD DCS DCP nDE OV OED

Bit 15

Bit 14

Bit 13

Must be set to 1b

Must be set to 0b

nSD: Second DCLK Output. When this bit is 1b, the device only has one DCLK output and one OR output.

When this output is 0b, the device has two identical DCLK outputs and no OR output.

POR State: 1b

Bit 12

Bit 11

DCS: Duty Cycle Stabilizer. When this bit is set to 1b, a duty cycle stabilization circuit is applied to the

clock input. When this bit is set to 0b the stabilization circuit is disabled.

POR State: 1b

DCP: DDR Clock Phase. This bit only has an effect in the DDR mode. When this bit is set to 0b, the DCLK

edges are time-aligned with the data bus edges ("0° Phase"). When this bit is set to 1b, the DCLK edges

are placed in the middle of the data bit-cells ("90° Phase"), using the one-half speed DCLK shown in

Figure 4 as the phase reference.

POR State: 0b

Bit 10

Bit 9

Bit 8

nDE: DDR Enable. When this bit is set to 0b, data bus clocking follows the DDR mode whereby a data

word is output with each rising and falling edge of DCLK. When this bit is set to a 1b, data bus clocking

follows the SDR mode whereby each data word is output with either the rising or falling edge of DCLK,

as determined by the OutEdge bit.

POR State: 0b

OV: Output Voltage. This bit determines the LVDS outputs' voltage amplitude and has the same function

as the OutV pin that is used in the Non-extended Control Mode. When this bit is set to 1b, the normal

output amplitude is used. When this bit is set to 0b, the reduced output amplitude is used. See V_ODin

Converter Electrical Characteristics.

POR State: 1b

OED: Output Edge and Demultiplex Control. This bit has two functions. When the device is in SDR mode,

this bit selects the DCLK edge with which the data words transition and has the same effect as the OutEdge

pin in the Non-extended Control Mode. When this bit is set to 1b, the data outputs change with the rising

edge of DCLK+. When this bit is set to 0b, the data output changes with the falling edge of DCLK+. When

the device is in DDR mode, this bit selects the Non-demultiplexed Mode when set to 1b. When the bit set

to 0b, the device is programmed into the Demultiplexed Mode. If the device is in DDR and Non-

Demultiplexed Mode, then the DCLK has a 0° phase relationship with the data; it is not possible to select

the 90° phase relationship.

POR State: 0b

Bits 7:0

Must be set to 1b

IMPORTANT NOTE: It is recommended that this register should only be written upon power-up initialization as writing it may cause

disturbance on the DCLK output as this signal's basic configuration is changed.

32

ADC07D1520

I-Channel Offset

Addr: 2h (0010b)

Write only (0x007F)

D15 D14 D13 D12 D11 D10

D9

D8

D7

D6

1

D5

1

D4

1

D3

1

D2

1

D1

1

D0

1

(MSB)

Offset Value

(LSB) Sign

Bits 15:8 Offset Value. The input offset of the I-channel ADC is adjusted linearly and monotonically by the value in

this field. 00h provides a nominal value of zero offset, while FFh provides a nominal value of 45 mV of

offset. Thus, each code step provides 0.176 mV of offset.

POR State: 0000 0000 b

Bit 7

Sign bit. 0b gives positive offset, 1b gives negative offset, resulting in total offset adjustment of ±45 mV.

POR State: 0b

Bit 6:0

Must be set to 1b

I-Channel Full-Scale Voltage Adjust

Addr: 3h (0011b)

Write only (0x807F)

D15

D14 D13 D12 D11 D10

Adjust Value

D9

D8

D7

D6

1

D5

1

D4

1

D3

1

D2

1

D1

1

D0

1

(MSB)

(LSB)

Bit 15:7

Full Scale Voltage Adjust Value. The input full-scale voltage or gain of the I-channel is adjusted linearly

and monotonically with a 9 bit data value. The adjustment range is ±20% of the nominal 700 mV_P-P

differential value.

0000 0000 0

560mV_P-P

700mV_P-P

840mV_P-P

1000 0000 0 Default Value

1111 1111 1

For best performance, it is recommended that the value in this field be limited to the range of 0110 0000

0b to 1110 0000 0b, i.e., limit the amount of adjustment to ±15%. The remaining ±5% headroom allows

for the ADC's own full scale variation. A gain adjustment does not require ADC re-calibration.

POR State: 1000 0000 0b (no adjustment)

Bits 6:0

Must be set to 1b

33

ADC07D1520

Extended Configuration Register

Addr: 9h (1001b)

D15 D14 D13 D12 D11 D10

TPO RTD DEN IS DLF

Write only (0x03FF)

D9

1

D8

1

D7

1

D6

1

D5

1

D4

1

D3

1

D2

1

D1

1

D0

1

0

Bit 15

Bit 14

Bit 13

TPO: Test Pattern Output. When this bit is set 1b, the ADC is disengaged and a test pattern generator is

connected to the outputs including OR. This test pattern will work with the device in the SDR, DDR and

the Non-demux Modes (DES and Non-DES).

POR State: 0b

RTD: Resistor Trim Disable. When this bit is set to 1b, the input termination resistor is not trimmed during

the calibration cycle and the DCLK output remains enabled. Note that the ADC is calibrated regardless

of this setting.

POR State: 0b

DEN: DES Enable. Setting this bit to 1b enables the Dual Edge Sampling Mode. In this mode, the ADCs

in this device are used to sample and convert the same analog input in a time-interleaved manner,

accomplishing a sample rate of twice the input clock rate. When this bit is set to 0b, the device operates

in the Non-DES Modes.

POR State: 0b

Bit 12

IS: Input Select. When this bit is set to 0b the I-channel is operated upon by both ADCs. When this bit is

set to 1b the Q-channel is operated on by both ADCs.

POR State: 0b

Bit 11

Bit 10

Must be set to 0b

DLF: DES Low Frequency. When this bit is set 1b, the dynamic performance of the device is improved

when the input clock is less than 900 MHz.

POR State: 0b

Bits 9:0

Must be set to 1b

34

ADC07D1520

Q-Channel Offset

Addr: Ah (1010b)

Write only (0x007F)

D15 D14 D13 D12 D11 D10

D9

D8

D7

D6

1

D5

1

D4

1

D3

1

D2

1

D1

1

D0

1

(MSB)

Offset Value

(LSB) Sign

Bit 15:8

Offset Value. The input offset of the Q-channel ADC is adjusted linearly and monotonically by the value

in this field. 00h provides a nominal zero offset, while FFh provides a nominal 45 mV of offset. Thus, each

code step provides about 0.176 mV of offset.

POR State: 0000 0000 b

Bit 7

Sign bit. 0b gives positive offset, 1b gives negative offset.

POR State: 0b

Bit 6:0

Must be set to 1b

Q-Channel Full-Scale Voltage Adjust

Addr: Bh (1011b)

Write only (0x807F)

D15

D14 D13 D12 D11 D10

Adjust Value

D9

D8

D7

D6

1

D5

1

D4

1

D3

1

D2

1

D1

1

D0

1

(MSB)

(LSB)

Bit 15:7

Full Scale Voltage Adjust Value. The input full-scale voltage or gain of the Q-channel ADC is adjusted

linearly and monotonically with a 9 bit data value. The adjustment range is ±20% of the nominal 700

mV_P-Pdifferential value.

0000 0000 0

560 mV_P-P

700 mV_P-P

840 mV_P-P

1000 0000 0 Default Value

1111 1111 1

For best performance, it is recommended that the value in this field be limited to the range of 0110 0000

0b to 1110 0000 0b, i.e., limit the amount of adjustment to ±15%. The remaining ±5% headroom allows

for the ADC's own full scale variation. A gain adjustment does not require ADC re-calibration.

POR State: 1000 0000 0b (no adjustment)

Bits 6:0

Must be set to 1b

35

ADC07D1520

Sample Clock Phase Fine Adjust

Addr: Eh (1110b)

D15 D14 D13 D12 D11 D10

(MSB) Fine Phase Adjust

Write only (0x00FF)

D9

D8

D7

1

D6

1

D5

1

D4

1

D3

1

D2

1

D1

1

D0

1

(LSB)

Bits 15:8 Fine Phase Adjust. The phase of the ADC sampling clock is adjusted linearly and monotonically by the

value in this field. 00h provides a nominal zero phase adjustment, while FFh provides a nominal 50 ps of

delay. Thus, each code step provides about 0.2 ps of delay.

POR State: 0000 0000b

Bits 7:0

Must be set to 1b

Sample Clock Phase Intermediate/Coarse Adjust

Addr: Fh (1111b)

Write only (0x007F)

D15

POL

D14 D13 D12 D11 D10

Coarse Phase Adjust

D9

D8

D7

D6

1

D5

1

D4

1

D3

1

D2

1

D1

1

D0

1

Int Phase Adjust

Bit 15

Polarity Select. When this bit is selected, the polarity of the ADC sampling clock is inverted.

POR State: 0b

Bits 14:10 Coarse Phase Adjust. Each code value in this field delays the sample clock by approximately 65 ps. A

value of 00000b in this field causes zero adjustment.

POR State: 00000b

Bits 9:7

Intermediate Phase Adjust. Each code value in this field delays the sample clock by approximately 11 ps.

A value of 000b in this field causes zero adjustment. Maximum combined adjustment using Coarse Phase

Adjust and Intermediate Phase adjust is approximately 2.1ns.

POR State: 000b

Bits 6:0

Must be set to 1b

1.4.1 Clock Phase Adjust

This is a feature intended to help the system designer remove small imbalances in clock distribution traces at the board level when

multiple ADCs are used. However, enabling this feature will reduce the dynamic performance (ENOB, SNR, SFDR) some finite

amount. The amount of degradation increases with the amount of adjustment applied. The user is strongly advised to (a) use the

minimal amount of adjustment; and (b) verify the net benefit of this feature in his system before relying on it.

1.4.2 DCLK Output During Register Programming

When programming the Configuration register, the DCLK output may be disrupted and is invalid. The DCLK output is not valid until

the register data has not been completely shifted and latched into the register and the register is in a known programmed state.

To minimize disrupting the DCLK output, it is recommend that the Configuration Register only be programmed when necessary.

For example, if a user wishes to enable the test pattern, only the Test Pattern register should be programmed. A user should avoid

developing software routines which program all the registers when the data contents of only one register is being modified.

36

ADC07D1520

1.5 MULTIPLE ADC SYNCHRONIZATION

The ADC07D1520 has the capability to precisely reset its sampling clock input to DCLK output relationship as determined by the

user-supplied DCLK_RST pulse. This allows multiple ADCs in a system to have their DCLK (and data) outputs transition at the

same time with respect to the shared CLK input that all the ADCs use for sampling.

The DCLK_RST signal must observe some timing requirements that are shown in Figure 7, Figure 8 and Figure 9 of the Timing

Diagrams. The DCLK_RST pulse must be of a minimum width and its deassertion edge must observe setup and hold times with

respect to the CLK input rising edge. These timing specifications are listed as t_PWR, t_RSand t_RHin the Converter Electrical Char-

acteristics.

The DCLK_RST signal can be asserted asynchronously to the input clock. If DCLK_RST is asserted, the DCLK output is held in a

designated state. The state in which DCLK is held during the reset period is determined by the mode of operation (SDR or DDR)

and the setting of the Output Edge configuration pin or bit. (Refer to Figure 7, Figure 8 and Figure 9 for the DCLK reset state

conditions). Therefore, depending upon when the DCLK_RST signal is asserted, there may be a narrow pulse on the DCLK line

during this reset event. When the DCLK_RST signal is de-asserted in synchronization with the CLK rising edge, there are three or

four CLK cycles of systematic delay and the next CLK falling edge synchronizes the DCLK output with those of other ADC07D1520s

in the system. The DCLK output is enabled again after a constant delay (relative to the input clock frequency) which is equal to the

CLK input to DCLK output delay (t_OD). The device always exhibits this delay characteristic in normal operation. The user has the

option of using a single-ended DCLK_RST signal, but a differential DCLK_RST is strongly recommended due to its superior timing

specifications.

As shown in Figure 7, Figure 8, and Figure 9 of the Timing Diagrams, there is a delay from the deassertion of DCLK_RST to the

reappearance of DCLK, which is equal to several CLK cycles of delay plus t_OD. Note that the deassertion of DCLK_RST is not

latched in until the next falling edge of CLK. For 1:2 Demux 0° Mode, there are four CLK cycles of delay; for all other modes, there

are three CLK cycles of delay.

If the device is not programmed to allow DCLK to run continuously, DCLK will become inactive during a calibration cycle. Therefore,

it is strongly recommended that DCLK only be used as a data capture clock and not as a system clock.

The DCLK_RST pin should NOT be brought high while the calibration process is running (while CalRun is high). Doing so could

cause a glitch in the digital circuitry, resulting in corruption and invalidation of the calibration.

1.6 ADC TEST PATTERN

To aid in system debug, the ADC07D1520 has the capability of providing a test pattern at the four output ports completely inde-

pendent of the input signal. The ADC is disengaged and a test pattern generator is connected to the outputs, including OR+/-. The

test pattern output is the same in DES Mode and Non-DES Mode. Each port is given a 7-bit word, alternating between 1's and 0's

as described in the Table 6 and Table 7.

TABLE 6. Test Pattern by Output Port

in 1:2 Demultiplex Mode

Time

T0

Qd

00h

7Fh

00h

7Fh

00h

7Fh

00h

7Fh

00h

...

Id

Q

I

OR

0

Comments

01h

7Eh

01h

7Eh

01h

7Eh

01h

7Eh

01h

...

01h 02h

7Eh 7Dh

01h 02h

7Eh 7Dh

01h 02h

7Eh 7Dh

01h 02h

7Eh 7Dh

01h 02h

T1

1

Pattern

Sequence

n

T2

0

T3

1

T4

0

T5

0

T6

1

Pattern

Sequence

n+1

T7

0

T8

1

T9

0

T10

T11

0

Pattern

Sequence n+2

...

With the part programmed into the Non-demultiplex Mode, the test pattern’s order will be as described in Table 7.

37

ADC07D1520

TABLE 7. Test Pattern by Output Port in

Non-demultiplex Mode

Time

T0

Q

I

OR

0

Comments

00h

7Fh

00h

7Fh

00h

7Fh

00h

7Fh

00h

7Fh

...

01h

7Eh

01h

7Eh

01h

7Eh

01h

7Eh

01h

7Eh

...

T1

1

T2

0

T3

0

Pattern

Sequence

n

T4

1

T5

1

T6

0

T7

0

T8

1

T9

0

T10

T11

T12

T13

T14

T15

0

1

Pattern

Sequence

n+1

0

1

...

Depending upon how it is initiated, the I- and the Q- channels' test patterns may or may not be synchronized. Either I and Id or Q

and Qd patterns may be behind by one DCLK.

To ensure that the test pattern starts synchronously in each port, set DCLK_RST while writing the Test Pattern Output bit in the

Extended Configuration Register. The pattern appears at the data output ports when DCLK_RST is cleared low. The test pattern

will work at speed and with the device in the SDR, DDR and the Non-demux Modes (DES and Non-DES).

38

ADC07D1520

2.0 Applications Information

2.1 THE REFERENCE VOLTAGE

The reference voltage for the ADC07D1520 is derived from a 1.254V bandgap reference, a buffered version of which, is made

available at V_BG(pin 31) for the user.

This output has an output current capability of ±100 μA and should be buffered if more current than this is required.

The internal bandgap-derived reference voltage has a nominal value of V_IN, as determined by the FSR pin and described in1.1.4

The Analog Inputs.

There is no provision for the use of an external reference voltage, but the full-scale input voltage can be adjusted through a

Configuration Register in the Extended Control Mode, as explained in 1.2 NON-EXTENDED AND EXTENDED CONTROL

MODE.

Differential input signals up to the chosen full-scale level will be digitized to 7 bits. Signal excursions beyond the full-scale range

will be clipped at the output. These large signal excursions will also activate the OR output for the time that the signal is out of

range. See 2.2.3 Out Of Range Indication.

One extra feature of the V_BGpin is that it can be used to raise the common mode voltage level of the LVDS outputs. The output

offset voltage (V_OS) is typically 800 mV when the V_BGpin is used as an output or left floating. To raise the LVDS offset voltage to

the typical value, the V_BGpin can be connected directly to the supply rail.

2.2 THE ANALOG INPUT

The analog input is differential and the signal source may be a.c. or d.c. coupled. In the Non-extended Control Mode, the full-scale

input range is selected using the FSR pin as specified in the Converter Electrical Characteristics. In the Extended Control Mode,

the full-scale input range is selected by programming the Full-Scale Voltage Adjust register through the Serial Interface. For best

performance when adjusting the input full-scale range in the Extended Control Mode, refer to 1.4 REGISTER DESCRIPTION for

guidelines on limiting the amount of adjustment.

Table 8 gives the input to output relationship with the FSR pin high when the Non-extended Control Mode is used. With the FSR

pin grounded, the millivolt values in Table 8 are reduced to 75% of the values indicated. In the Extended Control Mode, these values

will be determined by the full scale range and offset settings in the Control Registers.

TABLE 8. Differential Input To Output Relationship

(Non-Extended Control Mode, FSR High)

V_IN+

V_IN−

Output Code

000 0000

V_CM− 217.5 mV V_CM+ 217.5 mV

V_CM− 109 mV

V_CM

V_CM+ 109 mV

V_CM

010 0000

011 1111 /

100 0000

V_CM+ 109 mV

V_CM−109 mV

110 0000

111 1111

V_CM+ 217.5 mV V_CM− 217.5 mV

The buffered analog inputs simplify the task of driving these inputs so that the RC pole which is generally used at sampling ADC

inputs is not required. If the user desires to place an amplifier circuit before the ADC, care should be taken in choosing an amplifier

with adequate noise and distortion performance, and adequate gain at the frequencies used for the application.

Note that a precise d.c. common mode voltage must be present at the ADC inputs. This common mode voltage, V_CMO, is provided

on-chip when a.c. input coupling is used and the input signal is a.c. coupled to the ADC.

When the inputs are a.c. coupled, the V_CMOoutput must be grounded, as shown in Figure 11. This causes the on-chip V_CMOvoltage

to be connected to the inputs through on-chip 50 kΩ resistors.

IMPORTANT NOTE: An analog input channel that is not used (e.g. in DES Mode) should be connected to a.c. ground (i.e., ca-

pacitors to ground) when the inputs are a.c. coupled. Do not connect an unused analog input directly to ground.

30194144

FIGURE 11. V_CMODrive for A.C. Coupled Differential Input

39

ADC07D1520

When the d.c. coupled mode is used, a common mode voltage must be provided at the differential inputs. This common mode

voltage should track the V_CMOoutput pin. Note that the V_CMOoutput potential will change with temperature. The common mode

output of the driving device should track this change.

IMPORTANT NOTE: An analog input channel that is not used (e.g. in DES Mode) should be tied to the V_CMOvoltage when the

inputs are d.c. coupled. Do not connect unused analog inputs to ground.

Full-scale distortion performance falls off rapidly as the input common mode voltage deviates from V_CMO. This is a direct

result of using a very low supply voltage to minimize power. Keep the input common voltage within 50 mV of V_CMO

.

Performance is as good in the d.c. coupled mode as it is in the a.c. coupled mode, provided the input common mode voltage at

both analog inputs remains within 50 mV of V_CMO

.

2.2.1 Single-Ended Input Signals

There is no provision for the ADC07D1520 to adequately process single-ended input signals. The best way to handle single-ended

signals is to convert them to differential signals before presenting them to the ADC. The easiest way to accomplish single-ended

to differential signal conversion is with an appropriate balun-connected transformer, as shown in Figure 12.

30194143

FIGURE 12. Single-Ended to Differential Signal Conversion Using a Balun

Figure 12 is a generic depiction of a single-ended to differential signal conversion using a balun. The circuitry specific to the balun

will depend upon the type of balun selected and the overall board layout. It is recommended that the system designer contact the

manufacturer of the balun in order to aid in designing the best performing single-ended to differential conversion circuit.

When selecting a balun, it is important to understand the input architecture of the ADC. There are specific balun parameters, of

which the system designer should be mindful. The impedance of the analog source should be matched to the ADC07D1520's on-

chip 100Ω differential input termination resistor. The range of this termination resistor is described in the Converter Electrical

Characteristics as the specification R_IN.

Also, the phase and amplitude balance are important. The lowest possible phase and amplitude imbalance is desired when selecting

a balun. The phase imbalance should be no more than ±2.5° and the amplitude imbalance should be limited to less than 1dB at

the desired input frequency range. Finally, when selecting a balun, the VSWR (Voltage Standing Wave Ratio), bandwidth and

insertion loss of the balun should also be considered. The VSWR aids in determining the overall transmission line termination

capability of the balun when interfacing to the ADC input. The insertion loss should be considered so that the signal at the balun

output is within the specified input range of the ADC; see V_INin the Converter Electrical Characteristics.

2.2.2. D.C. Coupled Input Signals

When d.c. coupling to the ADC07D1520 analog inputs, single-ended to differential conversion may be easily accomplished with

the LMH6555, as shown in Figure 13. In such applications, the LMH6555 performs the task of single-ended to differential conversion

while delivering low distortion and noise, as well as output balance, that supports the operation of the ADC07D1520. Connecting

the ADC07D1520 V_CMOpin to the V_{CM_REF}pin of the LMH6555, via an appropriate buffer, will ensure that the common mode input

voltage meets the requirements for optimum performance of the ADC07D1520. The LMV321 was chosen to buffer V_CMDfor its low

voltage operation and reasonable offset voltage.

The output current from the ADC07D1520 V_CMOpin should be limited to 100 μA.

40

ADC07D1520

30194155

FIGURE 13. Example of Using LM6555 for D.C. Coupled Input

In Figure 13, R_ADJ-and R_ADJ+are used to adjust the differential offset that can be measured at the ADC inputs V_IN+and V_IN-with

the LMH6555's input terminated to ground as shown, but not driven and with no R_ADJresistors present. An unadjusted positive

offset with reference to V_IN-greater than |15mV| should be reduced with a resistor in the R_ADJ-position. Likewise, an unadjusted

negative offset with reference to V_IN-greater than |15mV| should be reduced with a resistor in the R_ADJ+position. Table 9 gives

suggested R_ADJ-and R_ADJ+values for various unadjusted differential offsets to bring the V_IN+and V_IN-offset back to within

|15mV|.

TABLE 9. Resistor Values for Offset Adjustment

Unadjusted Offset Reading

0mV to 10mV

Resistor Value

no resistor needed

20.0kΩ

11mV to 30mV

31mV to 50mV

10.0kΩ

51mV to 70mV

6.81kΩ

71mV to 90mV

4.75kΩ

91mV to 110mV

3.92kΩ

2.2.3 Out Of Range Indication

When the conversion result is clipped, the Out of Range (OR) output is activated such that OR+ goes high and OR- goes low. This

output is active as long as accurate data on either or both of the buses would be outside the range of 00h to FFh. When the device

is programmed to provide a second DCLK output, the OR signals become DCLK2. Refer to 1.4 REGISTER DESCRIPTION.

2.2.4 Full-Scale Input Range

As with all A/D Converters, the input range is determined by the value of the ADC's reference voltage. The reference voltage of

the ADC07D1520 is derived from an internal band-gap reference. The FSR pin controls the effective reference voltage of the

ADC07D1520 such that the differential full-scale input range at the analog inputs is a normal amplitude with the FSR pin high, or

a reduced amplitude with FSR pin low; see V_INin the Converter Electrical Characteristics. The best SNR is obtained with FSR high,

but better distortion and SFDR are obtained with the FSR pin low. The LMH6555 of Figure 13 is suitable for any Full Scale Range.

2.3 THE CLOCK INPUTS

The ADC07D1520 has differential LVDS clock inputs, CLK+ and CLK-, which must be driven with an a.c. coupled, differential clock

signal. Although the ADC07D1520 is tested and its performance is guaranteed with a differential 1.5 GHz clock, it will typically

function well with input clock frequency range; see f_CLK(min) and f_CLK(max) in the Converter Electrical Characteristics. The clock

inputs are internally terminated and biased. The input clock signal must be capacitively coupled to the clock pins as indicated in

Figure 14.

Operation up to the sample rates indicated in the Converter Electrical Characteristics is typically possible if the maximum ambient

temperatures indicated are not exceeded. Operating at higher sample rates than indicated for the given ambient temperature may

result in reduced device reliability and product lifetime. This is because of the higher power consumption and die temperatures at

high sample rates. Important also for reliability is proper thermal management. See 2.6.2 Thermal Management.

41

ADC07D1520

30194147

FIGURE 14. Differential (LVDS) Input Clock Connection

The differential input clock line pair should have a characteristic impedance of 100Ω and (when using a balun), be terminated at

the clock source in that (100Ω) characteristic impedance. The input clock line should be as short and as direct as possible. The

ADC07D1520 clock input is internally terminated with an untrimmed 100Ω resistor.

Insufficient input clock levels will result in poor dynamic performance. Excessively high input clock levels could cause a change in

the analog input offset voltage. To avoid this, keep the input clock level (V_ID) within the range specified in the Converter Electrical

Characteristics.

The low and high times of the input clock signal can affect the performance of any A/D Converter. The ADC07D1520 features a

duty cycle clock correction circuit which can maintain performance over the 20%-to-80% specified duty cycle range, even in DES

Mode. The ADC will meet its performance specification if the input clock high and low times are maintained within the duty cycle

range; see the Converter Electrical Characteristics.

High speed, high performance ADCs such as the ADC07D1520 require a very stable input clock signal with minimum phase noise

or jitter. ADC jitter requirements are defined by the ADC resolution (number of bits), maximum ADC input frequency and the input

signal amplitude relative to the ADC input full scale range. The maximum jitter (the sum of the jitter from all sources) allowed to

prevent a jitter-induced reduction in SNR is found to be

t_J(MAX)= ( V_INFSR/ V_IN(P-P)) x (1/(2^(N+1)x π x f_IN))

where t_J(MAX)is the rms total of all jitter sources in seconds, V_IN(P-P)is the peak-to-peak analog input signal, V_INFSRis the full-scale

range of the ADC, "N" is the ADC resolution in bits and f_INis the maximum input frequency, in Hertz, at the ADC analog input.

Note that the maximum jitter described above is the RSS sum of the jitter from all sources, including that in the ADC input clock,

that added by the system to the ADC input clock and input signals and that added by the ADC itself. Since the effective jitter added

by the ADC is beyond user control, the best the user can do is to keep the sum of the externally added input clock jitter and the

jitter added by the analog circuitry to the analog signal to a minimum.

Input clock amplitudes above those specified in the Converter Electrical Characteristics may result in increased input offset voltage.

This would cause the converter to produce an output code other than the expected 63/64 when both input pins are at the same

potential.

2.4 CONTROL PINS

Six control pins (without the use of the serial interface) provide a wide range of possibilities in the operation of the ADC07D1520

and facilitate its use. These control pins provide Full-Scale Input Range setting, Calibration, Calibration Delay, Output Edge Syn-

chronization choice, LVDS Output Level choice and a Power Down feature.

2.4.1 Full-Scale Input Range Setting

The input full-scale range can be selected with the FSR control input (pin 14) in the Non-extended Control Mode of operation. The

input full-scale range is specified as V_INin the Converter Electrical Characteristics. In the Extended Control Mode, the input full-

scale range may be programmed using the Full-Scale Adjust Voltage register. See 2.2 THE ANALOG INPUT for more information.

2.4.2 Calibration

The ADC07D1520 calibration must be run to achieve specified performance. The calibration procedure is run automatically upon

power-up and can be run any time on-command via the CAL pin (30) or the Calibration register (Addr: 0h, Bit 15). The calibration

procedure is exactly the same whether there is an input clock present upon power up or if the clock begins some time after

application of power. The CalRun output indicator is high while a calibration is in progress. Note that the DCLK outputs are not

active during a calibration cycle by default, therefore it is not recommended to use these signals as a system clock unless the

Resistor Trim Disable feature is used (Reg. 9h). The DCLK outputs are continuously present at the output only when the Resistor

Trim Disable is active.

2.4.2.1 Power-On Calibration

Power-on calibration begins after a time delay following the application of power. This time delay is determined by the setting of

CalDly.

The calibration process will be not be performed if the CAL pin is high at power up. In this case, the calibration cycle will not begin

until the on-command calibration conditions are met. The ADC07D1520 will function with the CAL pin held high at power up, but

no calibration will be done and performance will be impaired. A manual calibration, however, may be performed after powering up

with the CAL pin high. See 2.4.2.2 On-Command Calibration.

42

ADC07D1520

The internal power-on calibration circuitry comes up in an unknown logic state. If the input clock is not running at power up and the

power on calibration circuitry is active, it will hold the analog circuitry in power down and the power consumption will typically be

less than 200 mW. The power consumption will be normal after the clock starts.

2.4.2.2 On-Command Calibration

To initiate an on-command calibration, either bring the CAL pin high for a minimum of t_{CAL_H}input clock cycles after it has been

low for a minimum of t_{CAL_L}input clock cycles or perform the same operation via the CAL bit in the Calibration register. Holding the

CAL pin high upon power up will prevent execution of power-on calibration until the CAL pin is low for a minimum of t_{CAL_L}input

clock cycles, then brought high for a minimum of another t_{CAL_H}input clock cycles. The calibration cycle will begin t_{CAL_H}input clock

cycles after the CAL pin is thus brought high. The CalRun signal should be monitored to determine when the calibration cycle has

completed.

The minimum t_{CAL_L}and t_{CAL_H}input clock cycle sequences are required to ensure that random noise does not cause a calibration

to begin when it is not desired. For best performance, a calibration should be performed 20 seconds or more after power up and

repeated when the operating temperature changes significantly, relative to the specific system design performance requirements.

By default, on-command calibration also includes calibrating the input termination resistance and the ADC. However, since the

input termination resistance, once trimmed at power-up, changes marginally with temperature, the user has the option to disable

the input termination resistor trim, which will guarantee that the DCLK is continuously present at the output during subsequent

calibration. The Resistor Trim Disable (RTD) can be programmed in register 9h when in the Extended Control Mode. Refer to 1.4

REGISTER DESCRIPTION for register programming information.

2.4.2.3 Calibration Delay

The CalDly input (pin 127) is used to select one of two delay times after the application of power to the start of calibration, as

described in 1.1.1 Calibration. The calibration delay values allow the power supply to come up and stabilize before calibration takes

place. With no delay or insufficient delay, calibration would begin before the power supply is stabilized at its operating value and

result in non-optimal calibration coefficients. If the PD pin is high upon power-up, the calibration delay counter will be disabled until

the PD pin is brought low. Therefore, holding the PD pin high during power up will further delay the start of the power-up calibration

cycle. The best setting of the CalDly pin depends upon the power-on settling time of the power supply.

Note that the calibration delay selection is not possible in the Extended Control Mode and the short delay time is used.

2.4.3 Output Edge Synchronization

DCLK signals are available to latch the converter output data into external circuitry. The output data can be synchronized with either

edge of these DCLK signals. That is, the output data transition can be set to occur with either the rising edge or the falling edge of

the DCLK signal, so that either edge of that DCLK signal can be used to latch the output data into the receiving circuit.

When OutEdge (pin 4) is high, the output data is synchronized with the rising edge of the DCLK+ (pin 82). When OutEdge is low,

the output data is synchronized with the falling edge of DCLK+.

At the very high speeds, of which the ADC07D1520 is capable, slight differences in the lengths of the DCLK and data lines can

mean the difference between successful and erroneous data capture. The OutEdge pin may be used to capture data on the DCLK

edge that best suits the application circuit and layout.

2.4.4 LVDS Output Level Control

The output level can be set to one of two levels with OutV (pin 3). The strength of the output drivers is greater with OutV logic high.

With OutV logic low, there is less power consumption in the output drivers, but the lower output level means decreased noise

immunity.

For short LVDS lines and low noise systems, satisfactory performance may be realized with the OutV input low. If the LVDS lines

are long and/or the system in which the ADC07D1520 is used is noisy, it may be necessary to tie the OutV pin high.

2.4.5 Dual Edge Sampling

The Dual Edge Sampling (DES) feature causes one of the two input pairs to be routed to both ADCs. The other input pair is

deactivated. One of the ADCs samples the input signal on the rising input clock edge (duty cycle corrected); the other ADC samples

the input signal on the falling input clock edge (duty cycle corrected). If the device is in the 1:4 Demux DES Mode, the result is an

output data rate 1/4 that of the interleaved sample rate, which is twice the input clock frequency. Data is presented in parallel on

all four output buses in the following order: DQd, DId, DQ, DI. If the device is the Non-demux DES Mode, the result is an output

data rate 1/2 that of the interleaved sample rate. Data is presented in parallel on two output buses in the following order: DQ, DI.

To use this feature in the Non-extended Control Mode, allow pin 127 to float and the signal at the I-channel input will be sampled

by both converters. The Calibration Delay will then only be a short delay.

In the Extended Control Mode, either input may be used for dual edge sampling. See 1.1.5.1 Dual-Edge Sampling.

2.4.6 Power Down Feature

The Power Down pins (PD and PDQ) allow the ADC07D1520 to be entirely powered down (PD) or the Q-channel to be powered

down and the I-channel to remain active (PDQ). See 1.1.7 Power Down for details on the power down feature.

The digital data output pins are put into a high impedance state when the PD pin for the respective channel is high. Upon return to

normal operation, the pipeline will contain meaningless information and must be flushed.

If the PD input is brought high while a calibration is running, the device will not go into power down until the calibration sequence

is complete. However, if power is applied and PD is already high, the device will not begin the calibration sequence until the PD

input goes low. If a manual calibration is requested while the device is powered down, the calibration will not begin at all. That is,

the manual calibration input is completely ignored in the power down state.

43

ADC07D1520

2.5 THE DIGITAL OUTPUTS

The ADC07D1520 normally demultiplexes the output data of each of the two ADCs on the die onto two LVDS output buses (total

of four buses, two for each ADC). For each of the two converters, the results of successive conversions started on the odd falling

edges of the CLK+ pin are available on one of the two LVDS buses, while the results of conversions started on the even falling

edges of the CLK+ pin are available on the other LVDS bus. This means that, the word rate at each LVDS bus is 1/2 the AD-

C07D1520 input clock rate and the two buses must be multiplexed to obtain the entire 1.5 GSPS conversion result.

Since the minimum recommended input clock rate for this device is 200 MSPS (in 1:2 Demux Non-DES Mode), the effective rate

can be reduced to as low as 100 MSPS by using the results available on just one of the two LVDS buses and a 200 MHz input

clock, decimating the 200 MSPS data by two.

There is one LVDS output clock pair (DCLK+/-) available for use to latch the LVDS outputs on all buses. There is also a second

LVDS output clock pair (DCLK2+/-) which is optionally available for the same purpose. Whether the data is sent at the rising or

falling edge of DCLK is determined by the sense of the OutEdge pin, as described in 2.4.3 Output Edge Synchronization.

Double Data Rate (DDR) clocking can also be used. In this mode, a word of data is presented with each edge of DCLK, reducing

the DCLK frequency to 1/4 the input clock frequency. See the Timing Diagrams for details.

The OutV pin is used to set the LVDS differential output levels. See 2.4.4 LVDS Output Level Control.

The output format is Offset Binary. Accordingly, a full-scale input level with V_IN+ positive with respect to V_IN− will produce an output

code of all ones; a full-scale input level with V_IN− positive with respect to V_IN+ will produce an output code of all zeros; when V_IN+

and V_IN− are equal, the output code will vary between codes 63 and 64. A non-demultiplexed mode of operation is available for

those cases where the digital ASIC is capable of higher speed operation.

2.5.1 Terminating RSV Pins

The RSV pins can be connected to allow a given hardware design to support both the ADC07D1520 as well as the ADC08D1020

and ADC08D1520. The components shown in the diagram below should be installed when using the ADC07D1520 to ensure the

data inputs to the capture device are set to a known logic state. When using either of the 8 bit ADCs the terminating resistors should

not be installed.

30194136

FIGURE 15. Terminating RSV+/− Pins

2.6 POWER CONSIDERATIONS

A/D converters draw sufficient transient current to corrupt their own power supplies if not adequately bypassed. A 33 µF capacitor

should be placed within an inch (2.5 cm) of the A/D converter power pins. A 0.1 µF capacitor should be placed as close as possible

to each V_Apin, preferably within one-half centimeter. Leadless chip capacitors are preferred because they have low lead inductance.

The V_Aand V_DRsupply pins should be isolated from each other to prevent any digital noise from being coupled into the analog

portions of the ADC. A ferrite choke, such as the JW Miller FB20009-3B, is recommended between these supply lines when a

common source is used for them.

As is the case with all high speed converters, the ADC07D1520 should be assumed to have little power supply noise rejection. Any

power supply used for digital circuitry in a system where a lot of digital power is being consumed should not be used to supply

power to the ADC07D1520. The ADC supplies should be the same supply used for other analog circuitry, if not a dedicated supply.

2.6.1 Supply Voltage

The ADC07D1520 is specified to operate with a supply voltage of 1.9V ±0.1V. It is very important to note that, while this device will

function with slightly higher supply voltages, these higher supply voltages may reduce product lifetime.

No pin should ever have a voltage on it that is in excess of the supply voltage or below ground by more than 150 mV, not even on

a transient basis. This can be a problem upon application of power and power shut-down. Be sure that the supplies to circuits

driving any of the input pins, analog or digital, do not come up any faster than does the voltage at the ADC07D1520 power pins.

The Absolute Maximum Ratings should be strictly observed, even during power up and power down. A power supply that produces

a voltage spike at turn-on and/or turn-off of power can destroy the ADC07D1520. The circuit of Figure 16 will provide supply

overshoot protection.

44

ADC07D1520

Many linear regulators will produce output spiking at power-on unless there is a minimum load provided. Active devices draw very

little current until their supply voltages reach a few hundred millivolts. The result can be a turn-on spike that can destroy the

ADC07D1520, unless a minimum load is provided for the supply. The 100Ω resistor at the regulator output provides a minimum

output current during power-up to ensure there is no turn-on spiking.

In the circuit of Figure 16, an LM317 linear regulator is satisfactory if its input supply voltage is 4V to 5V. If a 3.3V supply is used,

an LM1086 linear regulator is recommended.

30194154

FIGURE 16. Non-Spiking Power Supply

The output drivers should have a supply voltage, V_DR, that is within the range specified in the Operating Ratings table. This voltage

should not exceed the V_Asupply voltage.

If the power is applied to the device without an input clock signal present, the current drawn by the device might be below 200 mA.

This is because the ADC07D1520 gets reset through clocked logic and its initial state is unknown. If the reset logic comes up in

the "on" state, it will cause most of the analog circuitry to be powered down, resulting in less than 100 mA of current draw. This

current is greater than the power down current because not all of the ADC is powered down. The device current will be normal after

the input clock is established.

2.6.2 Thermal Management

The ADC07D1520 is capable of impressive speeds and performance at very low power levels for its speed. However, the power

consumption is still high enough to require attention to thermal management. For reliability reasons, the die temperature should be

kept to a maximum of 130°C. That is, Ambient Temperature (T_A) plus ADC power consumption times Junction to Ambient Thermal

Resistance (θ_JA) should not exceed 130°C. This is not a problem if T_Ais kept to a maximum of +85°C as specified in the Operating

Ratings section.

The following are general recommendations for mounting exposed pad devices onto a PCB. They should be considered the starting

point in PCB and assembly process development. It is recommended that the process be developed based upon past experience

in package mounting.

The package of the ADC07D1520 has an exposed pad on its back that provides the primary heat removal path as well as excellent

electrical grounding to the printed circuit board. The land pattern design for pin attachment to the PCB should be the same as for

a conventional LQFP, but the exposed pad must be attached to the board to remove the maximum amount of heat from the package,

as well as to ensure best product parametric performance.

To maximize the removal of heat from the package, a thermal land pattern must be incorporated on the PC board within the footprint

of the package. The exposed pad of the device must be soldered down to ensure adequate heat conduction out of the package.

The land pattern for this exposed pad should be at least as large as the 5 x 5 mm of the exposed pad of the package and be located

such that the exposed pad of the device is entirely over that thermal land pattern. This thermal land pattern should be electrically

connected to ground. A clearance of at least 0.5 mm should separate this land pattern from the mounting pads for the package

pins.

30194121

FIGURE 17. Recommended Package Land Pattern

45

ADC07D1520

Since a large aperture opening may result in poor release, the aperture opening should be subdivided into an array of smaller

openings, similar to the land pattern of Figure 17.

To minimize junction temperature, it is recommended that a simple heat sink be built into the PCB. This is done by including a

copper area of about 2 square inches (6.5 square cm) on the opposite side of the PCB. This copper area may be plated or solder

coated to prevent corrosion, but should not have a conformal coating, which could provide some thermal insulation. Thermal vias

should be used to connect these top and bottom copper areas. These thermal vias act as "heat pipes" to carry the thermal energy

from the device side of the board to the opposite side of the board where it can be more effectively dissipated. The use of 9 to 16

thermal vias is recommended.

The thermal vias should be placed on a 1.2 mm grid spacing and have a diameter of 0.30 to 0.33 mm. These vias should be barrel

plated to avoid solder wicking into the vias during the soldering process as this wicking could cause voids in the solder between

the package exposed pad and the thermal land on the PCB. Such voids could increase the thermal resistance between the device

and the thermal land on the board, which would cause the device to run hotter.

If it is desired to monitor die temperature, a temperature sensor may be mounted on the heat sink area of the board near the thermal

vias. Allow for a thermal gradient between the temperature sensor and the ADC07D1520 die of θ_J-PADtimes typical power con-

sumption = 2.8°C/W x 1.8W = 5°C. Allowing for 6°C, including some margin for temperature drop from the pad to the temperature

sensor, would mean that maintaining a maximum pad temperature reading of 124°C will ensure that the die temperature does not

exceed 130°C. This calculation assumes that the exposed pad of the ADC07D1520 is properly soldered down and the thermal vias

are adequate. (The inaccuracy of the temperature sensor is in addition to the above calculation).

2.7 LAYOUT AND GROUNDING

Proper grounding and proper routing of all signals are essential to ensure accurate conversion. A single ground plane should be

used, instead of splitting the ground plane into analog and digital areas.

Since digital switching transients are composed largely of high frequency components, the skin effect implies that the total ground

plane copper weight will have little effect upon the logic-generated noise. Total surface area is more important than is total ground

plane volume. Coupling between the typically noisy digital circuitry and the sensitive analog circuitry can lead to poor performance

that may seem impossible to isolate and remedy. The solution is to keep the analog circuitry well separated from the digital circuitry.

High power digital components should not be located on or near any linear component or power supply trace or plane that services

analog or mixed signal components, as the resulting common return current path could cause fluctuation in the analog input “ground”

return of the ADC, causing excessive noise in the conversion result.

Generally, it is assumed that analog and digital lines should cross each other at 90° to avoid getting digital noise into the analog

path. In high frequency systems, however, avoid crossing analog and digital lines altogether. The input clock lines should be isolated

from ALL other lines, analog AND digital. The generally accepted 90° crossing should be avoided, as even a little coupling can

cause problems at high frequencies. Best performance at high frequencies is obtained with a straight signal path.

The analog input should be isolated from noisy signal traces to avoid coupling of spurious signals into the input. This is especially

important with the low level drive required of the ADC07D1520. Any external component (e.g., a filter capacitor) connected between

the converter's input and ground should be connected to a very clean point in the analog ground plane. All analog circuitry (input

amplifiers, filters, etc.) should be separated from any digital components.

2.8 DYNAMIC PERFORMANCE

The ADC07D1520 is a.c. tested and its dynamic performance is guaranteed. To meet the published specifications and avoid jitter-

induced noise, the clock source driving the CLK input must exhibit low rms jitter. The allowable jitter is a function of the input

frequency and the input signal level, as described in 2.3 THE CLOCK INPUTS.

It is good practice to keep the ADC input clock line as short as possible, to keep it well away from any other signals and to treat it

as a transmission line. Other signals can introduce jitter into the input clock signal. The clock signal can also introduce noise into

the analog path if not isolated from that path.

Best dynamic performance is obtained when the exposed pad at the back of the package has a good connection to ground. This

is because this path from the die to ground is a lower impedance than offered by the package pins.

2.9 USING THE SERIAL INTERFACE

The ADC07D1520 may be operated in the Non-extended Control Mode or in the Extended Control Mode. Table 10 and Table 11

describe the functions of pins 3, 4, 14 and 127 in the Non-extended Control Mode and the Extended Control Mode, respectively.

2.9.1 Non-Extended Control Mode Operation

Non-extended Control Mode operation means that the Serial Interface is not active and all controllable functions are controlled with

various pin settings. Pin 41 is the primary control of the Extended Control Mode enable function. When pin 41 is logic high, the

device is in the Non-extended Control Mode. If pin 41 is floating and pin 52 is floating or logic high, the Extended Control Enable

function is controlled by pin 14. The device has functions which are pin programmable when in the Non-extended Control Mode.

An example is the full-scale range; it is controlled in the Non-extended Control Mode by setting pin 14 logic high or low. Table 10

indicates the pin functions of the ADC07D1520 in the Non-extended Control Mode.

46

ADC07D1520

TABLE 10. Non-Extended Control Mode Operation

(Pin 41 Floating and Pin 52 Floating or Logic High)

3

Low

High

Floating

Reduced V_OD

OutEdge = Neg

CalDly Short

Reduced V_IN

Normal V_OD

OutEdge = Pos

CalDly Long

Normal V_IN

N/A

4

DDR

DES

127

14

Extended Control Mode

Pin 3 can be either logic high or low in the Non-extended Control Mode. Pin 14 must not be left floating to select this mode. See

1.2 NON-EXTENDED AND EXTENDED CONTROL MODE for more information.

Pin 4 can be logic high, logic low or left floating in the Non-extended Control Mode. In the Non-extended Control Mode, pin 4 logic

high or low defines the edge at which the output data transitions. See 2.4.3 Output Edge Synchronization for more information. If

this pin is floating, the output Data Clock (DCLK) is a Double Data Rate (DDR) clock (see 1.1.5.3 Double Data Rate and Single

Data Rate) and the output edge synchronization is irrelevant since data is clocked out on both DCLK edges.

Pin 127, if it is logic high or low in the Non-extended Control Mode, sets the calibration delay. If pin 127 is floating, the calibration

delay is short and the converter performs in DES Mode.

TABLE 11. Extended Control Mode Operation

(Pin 41 Logic Low or Pin 14 Floating and Pin 52 Floating or Logic High)

3

Function

SCLK (Serial Clock)

4

SDATA (Serial Data)

127

SCS (Serial Interface Chip Select)

2.10 COMMON APPLICATION PITFALLS

Failure to write all register locations when using extended control mode. When using the serial interface, all nine address

locations must be written at least once with the default or desired values before calibration and subsequent use of the ADC.

Driving the inputs (analog or digital) beyond the power supply rails. For device reliability, no input should go more than 150

mV below the ground pins or 150 mV above the supply pins. Exceeding these limits on even a transient basis may not only cause

faulty or erratic operation, but may impair device reliability. It is not uncommon for high speed digital circuits to exhibit undershoot

that goes more than a volt below ground. Controlling the impedance of high speed lines and terminating these lines in their char-

acteristic impedance should control overshoot.

Care should be taken not to overdrive the inputs of the ADC07D1520. Such practice may lead to conversion inaccuracies and even

to device damage.

Incorrect analog input common mode voltage in the d.c. coupled mode. As discussed in 1.1.4 The Analog Inputs and 2.2 THE

ANALOG INPUT, the Input common mode voltage must remain within 50 mV of the V_CMOoutput , which varies with temperature

and must also be tracked. Distortion performance will be degraded if the input common mode voltage is more than 50 mV from

V_CMO

.

Using an inadequate amplifier to drive the analog input. Use care when choosing a high frequency amplifier to drive the

ADC07D1520 as many high speed amplifiers will have higher distortion than the ADC07D1520, resulting in overall system perfor-

mance degradation.

Driving the V_BGpin to change the reference voltage. As mentioned in 2.1 THE REFERENCE VOLTAGE, the reference voltage

is intended to be fixed by FSR pin or Full-Scale Voltage Adjust register settings. Over driving this pin will not change the full scale

value, but can be used to change the LVDS common mode voltage from 0.8V to 1.2V by tying the V_BGpin to V_A.

Driving the clock input with an excessively high level signal. The ADC input clock level should not exceed the level described

in the Operating Ratings Table or the input offset could change.

Inadequate input clock levels. As described in 2.3 THE CLOCK INPUTS, insufficient input clock levels can result in poor perfor-

mance. Excessive input clock levels could result in the introduction of an input offset.

Using a clock source with excessive jitter, using an excessively long input clock signal trace, or having other signals

coupled to the input clock signal trace. This will cause the sampling interval to vary, causing excessive output noise and a

reduction in SNR performance.

Failure to provide adequate heat removal. As described in 2.6.2 Thermal Management, it is important to provide adequate heat

removal to ensure device reliability. This can be done either with adequate air flow or the use of a simple heat sink built into the

board. The backside pad should be grounded for best performance.

47

ADC07D1520

Physical Dimensions inches (millimeters) unless otherwise noted

NOTES: UNLESS OTHERWISE SPECIFIED

REFERENCE JEDEC REGISTRATION MS-026, VARIATION BFB.

128-Lead Exposed Pad LQFP

Order Number ADC07D1520CIYB

NS Package Number VNX128A

48

ADC07D1520

Notes

49

Notes

Incorporated


型号：	ADC07D1520
厂家：	TEXAS INSTRUMENTS
描述：	7 位、双路 1.5GSPS 或单路 3.0GSPS 模数转换器 (ADC) 转换器模数转换器
文件：	总53页 (文件大小：833K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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