AD9674KBCZ [ADI]
Octal Ultrasound AFE;
| 型号： | AD9674KBCZ |
| 厂家： | 
ADI |
| 描述： | Octal Ultrasound AFE |
| 文件： | 总48页 (文件大小：981K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Octal Ultrasound Analog Front End
Data Sheet
AD9674
FEATURES
GENERAL DESCRIPTION
8 channels of LNA, VGA, AAF, ADC, and digital RF decimator
Low power: 150 mW per channel, TGC mode, 40 MSPS;
62.5 mW per channel, CW mode; <30 mW in power-down
Time gain compensation (TGC) channel input referred noise:
0.82 nV/√Hz, maximum gain
Flexible power-down modes
Fast recovery from low power standby mode: <2 μs
Low noise preamplifier (LNA)
Input referred noise voltage: 0.78 nV/√Hz, gain = 21.6 dB
Programmable gain: 15.6 dB/17.9 dB/21.6 dB
0.1 dB compression: 1.00 V p-p/
0.75 V p-p/0.45 V p-p
Flexible active input impedance matching
Variable gain amplifier (VGA)
Attenuator range: 45 dB, linear in dB gain control
Postamplifier gain (PGA): 21 dB/24 dB/27 dB/30 dB
Antialiasing filter (AAF)
Programmable second-order low-pass filter (LPF) from 8 MHz
to 18 MHz or 13.5 MHz to 30 MHz and high-pass filter (HPF)
Analog-to-digital converter (ADC)
Signal-to-noise ratio (SNR): 75 dB, 14 bits up to 125 MSPS
Configurable serial low voltage differential signaling (LVDS)
Continuous wave (CW) Doppler mode harmonic rejection I/Q
demodulator
Individual programmable phase rotation
Dynamic range per channel: >160 dBFS/√Hz
Close in SNR: 156 dBc/√Hz, 1 kHz offset, −3 dBFS input
Radio frequency (RF) digital HPF and decimation by 2
10 mm × 10 mm, 144-ball CSP_BGA
The AD9674 is designed for low cost, low power, small size, and
ease of use for medical ultrasound. It contains eight channels of a
VGA with an LNA, a CW harmonic rejection I/Q demodulator
with programmable phase rotation, an AAF, an ADC, a digital
HPF, and RF decimation by 2.
Each channel features a maximum gain of up to 52 dB, a fully
differential signal path, and an active input preamplifier termination.
The channel is optimized for high dynamic performance and
low power in applications where a small package size is critical.
The LNA has a single-ended to differential gain that is selectable
through the serial port interface (SPI). Assuming a 15 MHz noise
bandwidth (NBW) and a 21.6 dB LNA gain, the LNA input SNR is
94 dB. In CW Doppler mode, each LNA output drives an I/Q
demodulator that has independently programmable phase
rotation with 16 phase settings.
Power-down of individual channels is supported to increase battery
life for portable applications. Standby mode allows quick power-up
for power cycling. In CW Doppler operation, the VGA, AAF, and
ADC are powered down. The ADC contains several features
designed to maximize flexibility and minimize system cost, such as
a programmable clock, data alignment, and programmable digital
test pattern generation. The digital test patterns include built in
fixed patterns, built in pseudorandom patterns, and custom
user defined test patterns entered via the SPI.
APPLICATIONS
Medical imaging/ultrasound
Nondestructive Testing (NDT)
Rev. A
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AD9674* PRODUCT PAGE QUICK LINKS
Last Content Update: 02/23/2017
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• AD9674: Octal Ultrasound AFE With RF Decimator Data
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AD9674
Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Analog Test Signal Generation................................................. 31
CW Doppler Operation............................................................. 32
Digital RF Decimator..................................................................... 33
Vector Profile .............................................................................. 33
RF Decimator.............................................................................. 34
Digital Test Waveforms.............................................................. 34
Digital block Power Saving scheme ......................................... 35
Serial Port Interface (SPI)................................................................ 36
Hardware Interface..................................................................... 36
Memory Map .................................................................................. 38
Reading the Memory Map Table.............................................. 38
Reserved Locations .................................................................... 38
Default Values............................................................................. 38
Logic Levels................................................................................. 38
Recommended Start-Up Sequence .......................................... 38
Memory Map Register Descriptions........................................ 46
Outline Dimensions....................................................................... 47
Ordering Guide .......................................................................... 47
Applications....................................................................................... 1
General Description......................................................................... 1
Revision History ............................................................................... 2
Functional Block Diagram .............................................................. 3
Specifications..................................................................................... 4
AC Specifications.......................................................................... 4
Digital Specifications ................................................................... 7
Switching Specifications .............................................................. 8
ADC Timing Diagram................................................................. 9
CW Doppler Timing Diagram ................................................... 9
Absolute Maximum Ratings.......................................................... 11
Thermal Impedance................................................................... 11
ESD Caution................................................................................ 11
Pin Configuration and Function Descriptions........................... 12
Typical Performance Characteristics ........................................... 15
TGC Mode................................................................................... 15
CW Doppler Mode..................................................................... 19
Theory of Operation ...................................................................... 20
TGC Operation........................................................................... 20
REVISION HISTORY
1/16—Revision A: Initial Version
Rev. A | Page 2 of 47
Data Sheet
AD9674
FUNCTIONAL BLOCK DIAGRAM
AVDD1 AVDD2
PDWN STBY
DVDD
DRVDD
CWQ+
CWQ–
CWI+
CWI–
LO-A TO LO-H
CWD I/Q
DEMODULATOR
LOSW-A TO LOSW-H
LI-A TO LI-H
DOUTA+ TO DOUTH+
DOUTA– TO DOUTH–
14-BIT
ADC
FILTER/
DECIMATOR
LNA
SERIALIZER
VGA
LVDS
AAF
LG-A TO LG-H
AD9674
8 CHANNELS
FCO+
FCO–
DCO+
DCO–
SERIAL
PORT
INTERFACE
DATA
RATE
MULTIPLIER
LO
REFERENCE
NCO
GENERATION
Figure 1.
Rev. A | Page 3 of 47
AD9674
Data Sheet
SPECIFICATIONS
AC SPECIFICATIONS
AVDD1 = 1.8 V, AVDD2 = 3.0 V, DVDD = 1.4 V, DRVDD = 1.8 V, 1.0 V internal ADC reference, full temperature range (0°C to 85°C),
f
IN = 5 MHz, local oscillator (LO) band mode, RS = 50 Ω, RFB = ∞ (unterminated), LNA gain = 21.6 dB, LNA bias = midhigh, programmable gain
amplifier (PGA) gain = 27 dB, analog gain control, VGAIN = (GAIN+) − (GAIN−) = 1.6 V, AAF LPF cutoff = fSAMPLE/3 in Mode I1/Mode II,1 AAF
LPF cutoff = fSAMPLE/4.5 in Mode III1/Mo de IV, 1 HPF cutoff = LPF cutoff/12.00, Mode I1 = fSAMPLE = 40 MSPS, Mode II1 = fSAMPLE = 65 MSPS,
Mode III1 = fSAMPLE = 80 MSPS, Mode IV1 = fSAMPLE = 125 MSPS, RF decimator bypassed, digital filter bypassed, and low power LVDS mode,
unless otherwise noted. All gain setting options are listed, which can be configured via SPI registers, and all power supply currents and power
dissipations are listed for the four mode settings (Mode I, Mode II, Mode III, and Mode IV).1
Table 1.
Parameter2
LNA CHARACTERISTICS
Gain
Test Conditions/Comments
Min
Typ
Max
Unit
Single-ended input to differential output
Single-ended input to single-ended
output
15.6/17.9/21.63
9.6/11.9/15.63
dB
dB
0.1 dB Input Compression Point
1 dB Input Compression Point
LNA gain = 15.6 dB
LNA gain = 17.9 dB
LNA gain = 21.6 dB
LNA gain = 15.6 dB
LNA gain = 17.9 dB
LNA gain = 21.6 dB
1.00
0.75
0.45
1.20
0.90
0.60
2.2
V p-p
V p-p
V p-p
V p-p
V p-p
V p-p
V
Input Common Mode (LI-x, LG-x)
Output Common Mode (LO-x)
Switch off
Switch on
High-Z
1.5
Ω
V
Output Common Mode (LOSW-x)
Input Resistance (LI-x)
Switch off
Switch on
RFB = 300 Ω
High-Z
1.5
50
Ω
V
Ω
RFB = 1350 Ω
RFB = ∞ (unterminated)
200
6
Ω
kΩ
Input Capacitance (LI-x)
20
pF
Input Referred Noise Voltage
RS = 0 Ω
LNA gain = 15.6 dB
LNA gain = 17.9 dB
LNA gain = 21.6 dB
Noise bandwidth = 15 MHz,
LNA gain = 21.6 dB
0.83
0.82
0.78
94
nV/√Hz
nV/√Hz
nV/√Hz
dB
Input SNR
Input Referred Noise Current
FULL CHANNEL (TGC) CHARACTERISTICS
AAF Low-Pass Cutoff
2.6
pA/√Hz
−3 dB, programmable, low band mode
−3 dB, programmable, high band mode
8
13.5
18
30
MHz
MHz
In Range AAF Bandwidth Tolerance
Group Delay Variation
Input Referred Noise Voltage
10
350
0.96
0.90
0.82
%
ps
nV/√Hz
nV/√Hz
nV/√Hz
f = 1 MHz to 18 MHz, VGAIN = −1.6 V to +1.6 V
LNA gain = 15.6 dB
LNA gain = 17.9 dB
LNA gain = 21.6 dB
Noise Figure
RS = 50 Ω
Active Termination Matched
LNA gain = 15.6 dB, RFB = 150 Ω
LNA gain = 17.9 dB, RFB = 200 Ω
LNA gain = 21.6 dB, RFB = 300 Ω
LNA gain = 15.6 dB
LNA gain = 17.9 dB
LNA gain = 21.6 dB
5.6
4.8
3.8
3.2
2.9
2.6
−30
dB
dB
dB
dB
dB
dB
dB
Unterminated
Correlated Noise Ratio
No signal, correlated/uncorrelated
Rev. A | Page 4 of 47
Data Sheet
AD9674
Parameter2
Output Offset
SNR
Test Conditions/Comments
Min
Typ
Max
Unit
−100
+100
LSB
fIN = 5 MHz at −12 dBFS, VGAIN = −1.6 V
fIN = 5 MHz at −1 dBFS, VGAIN = 1.6 V
fIN = 3.5 MHz at −1 dBFS, VGAIN = 0 V,
1 kHz offset
69
59
−130
dBFS
dBFS
dBc/√Hz
Close-In SNR
Second Harmonic
fIN = 5 MHz at −12 dBFS, VGAIN = −1.6 V
fIN = 5 MHz at −1 dBFS, VGAIN = 1.6 V
fIN = 5 MHz at −12 dBFS, VGAIN = −1.6 V
fIN = 5 MHz at −1 dBFS, VGAIN = 1.6 V
fRF1 = 5.015 MHz, fRF2 = 5.020 MHz,
ARF1 = −1 dBFS, ARF2 = −21 dBFS,
VGAIN = 1.6 V, IMD3 relative to ARF2
−70
−62
−61
−55
−54
dBc
dBc
dBc
dBc
dBc
Third Harmonic
Two-Tone Intermodulation Distortion
(IMD3)
Channel to Channel Crosstalk
fIN = 5 MHz at −1 dBFS
Overrange condition4
TA = 25°C
−60
−55
dB
dB
GAIN ACCURACY
Gain Law Conformance Error
−1.6 < VGAIN < −1.28 V
−1.28 V < VGAIN < +1.28 V
1.28 V < VGAIN < 1.6 V
VGAIN = 0 V, normalized for ideal AAF loss
−1.28 V < VGAIN < +1.28 V, 1 σ
0.4
dB
dB
dB
dB
dB
dB
−1.3
−1.3
+1.3
+1.3
−0.5
Linear Gain Error
Channel to Channel Matching
PGA Gain
0.1
21/24/27/303
GAIN CONTROL INTERFACE
Control Range
Control Common Mode
Input Impedance
Gain Range
Differential
GAIN+, GAIN−
GAIN+, GAIN−
−1.6
0.7
+1.6
0.9
V
V
0.8
10
45
14
3.5
750
MΩ
dB
dB/V
dB
ns
Scale Factor
Analog
Digital step size
Analog 45 dB change
Response Time
CW DOPPLER MODE
LO Frequency
fLO = fMLO/M
1
10
MHz
Phase Resolution
Per channel, 4LO5 mode
Per channel, 8LO5 mode, 16LO5 mode
CWI+, CWI−, CWQ+, CWQ−
Per CWI+, CWI−, CWQ+, and CWQ−,
each channel is enabled (2 × fLO and
baseband signal)
45
22.5
AVDD2/2
2.2
Degrees
Degrees
V
Output DC Bias (Single-Ended)
Output AC Current Range
2.5
mA
Transconductance (Differential)
Demodulated IOUT/VIN, per CWI+, CWI−,
CWQ+, and CWQ−
LNA gain = 15.6 dB
LNA gain = 17.9 dB
LNA gain = 21.6 dB
RS = 0 Ω, RFB = ∞
LNA gain = 15.6 dB
LNA gain = 17.9 dB
LNA gain = 21.6 dB
RS = 50 Ω, RFB = ∞
LNA gain = 15.6 dB
LNA gain = 17.9 dB
LNA gain = 21.6 dB
RS = 0 Ω, RFB = ∞
3.3
4.3
6.6
mA/V
mA/V
mA/V
Input Referred Noise Voltage
Noise Figure
1.6
1.3
1.0
nV/√Hz
nV/√Hz
nV/√Hz
5.7
4.5
3.4
dB
dB
dB
Dynamic Range
LNA gain = 15.6 dB
LNA gain = 17.9 dB
LNA gain = 21.6 dB
164
162
160
dBFS/√Hz
dBFS/√Hz
dBFS/√Hz
Rev. A | Page 5 of 47
AD9674
Data Sheet
Parameter2
Test Conditions/Comments
Min
Typ
Max
Unit
Close In SNR
−3 dBFS input, fRF = 2.5 MHz,
fLO = 40 MHz, 1 kHz offset,
156
dBc/√Hz
16LO5 mode, one channel enabled
−3 dBFS input, fRF = 2.5 MHz,
fLO = 40 MHz, 1 kHz offset,
161
−58
dBc/√Hz
dBc
16LO5 mode, eight channels enabled
Two-Tone Intermodulation Distortion
(IMD3)
fRF1 = 5.015 MHz, fRF2 = 5.020 MHz,
fLO = 80 MHz, ARF1 = −1 dBFS,
ARF2 = −21 dBFS, IMD3 relative to ARF2
LO Harmonic Rejection
−20
dBc
Quadrature Phase Error
I/Q Amplitude Imbalance
Channel to Channel Matching
I to Q, all phases, 1 σ
I to Q, all phases, 1 σ
Phase I to I, Q to Q, 1 σ
Amplitude I to I, Q to Q, 1 σ
Mode I/Mode II/Mode III/Mode IV1, 3
0.15
0.015
0.5
Degrees
dB
Degrees
dB
0.25
POWER SUPPLY
AVDD1
AVDD2
DVDD
DRVDD
IAVDD1
1.7
2.85
1.3
1.8
3.0
1.4
1.8
1.9
3.6
1.9
1.9
V
V
V
V
mA
mA
mA
mA
mA
1.7
TGC mode, LO band mode
CW Doppler mode
TGC mode, no signal, low band mode
TGC mode, no signal, high band mode
144/188/224/2943
4
230
239
140
IAVDD2
CW Doppler mode, eight channels
enabled
IDVDD
RF decimator enabled in Mode III1 and
47/75/57/913
30/48/42/653
mA
mA
Mode IV,1 digital HPF enabled
RF decimator enabled in Mode III1 and
Mode IV,1 digital HPF disabled
IDRVDD
ANSI-644 mode
Low power (IEEE 1596.3 similar) mode
125/170/128/1693
109/155/114/1543
mA
mA
Total Power Dissipation (Including
Output Drivers)
TGC mode, no signal, RF decimator
enabled in Mode III and Mode IV,
digital HPF disabled
1190/1385/
1365/16003
1325/1535/
1515/17653
mW
TGC mode, no signal, RF decimator
enabled in Mode III1 and Mode IV, 1
digital HPF enabled
1215/1425/
1385/16403
1350/1575/ mW
1535/18003
CW Doppler mode, eight channels
enabled
500
630
mW
Power-Down Dissipation
Standby Power Dissipation
ADC
30
mW
mW
Resolution
SNR
14
75
Bits
dB
fIN = 5 MHz
ADC REFERENCE
Output Voltage Error
Load Regulation at 1.0 mA
Input Resistance
VREF = 1 V
VREF = 1 V
50
mV
mV
kΩ
2
7.5
1 The ADC speed modes depending on the encoding clock rate.
2 For a complete set of definitions and information about how these tests were completed, see the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation.
3 The slashes mean that the four different power and current values are listed for the four different modes (Mode I, Mode II, Mode III, Mode IV).
4 The overrange condition is specified as 6 dB more than the full-scale input range.
5 The internal LO frequency, fLO, is generated from the supplied multiplier local oscillator frequency, fMLO, by dividing it up by a configurable divider value (M) that can be
4, 8, or 16; the MLO signal is named 4LO, 8LO, or 16LO, accordingly.
Rev. A | Page 6 of 47
Data Sheet
AD9674
DIGITAL SPECIFICATIONS
AVDD1 = 1.8 V, AVDD2 = 3.0 V, DVDD = 1.4 V, DRVDD = 1.8 V, 1.0 V internal ADC reference, full temperature range (0°C to 85°C), unless
otherwise noted.
Table 2.
Parameter1
Temperature
Min
Typ
Max
Unit
INPUTS (CLK+, CLK−, TX_TRIG+, TX_TRIG−)
Logic Compliance
Differential Input Voltage2
Input Voltage Range
Input Common-Mode Voltage
Input Resistance (Differential)
Input Capacitance
Full
Full
Full
Full
25°C
25°C
CMOS/LVDS/LVPECL
3.6
0.2
GND − 0.2
V p-p
V
V
kΩ
pF
AVDD1 + 0.2
0.9
15
4
INPUTS (MLO , RESET )
Logic Compliance
Full
Full
Full
Full
25°C
25°C
LVDS/LVPECL
Differential Input Voltage2
0.250
GND − 0.2
2 × AVDD2
AVDD2 + 0.2
V p-p
V
Input Voltage Range
Input Common-Mode Voltage
Input Resistance (Single-Ended)
Input Capacitance
AVDD2/2
20
1.5
V
kΩ
pF
LOGIC INPUTS (PDWN, STBY, SCLK, SDIO, ADDRx)
Logic 1 Voltage
Logic 0 Voltage
Input Resistance
Input Capacitance
Full
Full
25°C
25°C
1.2
1.2
DRVDD + 0.3
0.3
V
V
kΩ
pF
30 (26 for SDIO)
2 (5 for SDIO)
LOGIC INPUT (CSB)
Logic 1 Voltage
Logic 0 Voltage
Full
Full
DRVDD + 0.3
0.3
V
V
Input Resistance
Input Capacitance
25°C
25°C
26
2
kΩ
pF
LOGIC OUTPUT (SDIO)3
Logic 1 Voltage (IOH = 800 µA)
Logic 0 Voltage (IOL = 50 µA)
DIGITAL OUTPUTS (DOUTx+, DOUTx−), ANSI-644
Logic Compliance
Differential Output Voltage (VOD)
Output Offset Voltage (VOS)
Output Coding (Default)
Full
Full
1.79
V
V
0.05
Full
Full
Full
Full
LVDS
247
1.125
454
1.375
mV
V
Offset binary
LVDS
DIGITAL OUTPUTS (DOUTx+, DOUTx−), LOW POWER,
REDUCED SIGNAL OPTION
Logic Compliance
Differential Output Voltage (VOD)
Output Offset Voltage (VOS)
Output Coding (Default)
Full
Full
Full
Full
Full
Full
150
1.10
250
1.30
mV
V
Offset binary
LOGIC OUTPUT (GPO0/GPO1/GPO2/GPO3)
Logic 0 Voltage (IOL = 50 µA)
0.05
V
1 For a complete set of definitions and information about how these tests were completed, see the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation.
2 Specified for LVDS and LVPECL only.
3 Specified for 13 SDIO pins sharing the same connection.
Rev. A | Page 7 of 47
AD9674
Data Sheet
SWITCHING SPECIFICATIONS
AVDD1 = 1.8 V, AVDD2 = 3.0 V, DVDD = 1.4 V, DRVDD = 1.8 V, full temperature range (0°C to 85°C), RF decimator bypassed, and
digital HPF bypassed, unless otherwise noted.
Table 3.
Parameter1
CLOCK2
Temperature Min
Typ
Max
Unit
Clock Rate
40 MSPS (Mode I)
Full
Full
Full
Full
Full
Full
20.5
20.5
20.5
20.5
40
65
80
125
MHz
MHz
MHz
MHz
ns
65 MSPS (Mode II)
80 MSPS (Mode III)3
125 MSPS (Mode IV)4
Clock Pulse Width High (tEH)
Clock Pulse Width Low (tEL)
OUTPUT PARAMETERS2, 5
Propagation Delay (tPD)
Rise Time (tR) (20% to 80%)
3.75
3.75
ns
Full
Full
Full
Full
Full
Full
Full
Full
Full
25°C
25°C
25°C
25°C
Full
10.8 − 1.5 × tDCO
10.8 − 1.5 × tDCO
10.8
300
300
tSAMPLE/7
10.8
tFCO + (tSAMPLE/28)
tSAMPLE/28
tSAMPLE/28
225
10.8 + 1.5 × tDCO
10.8 + 1.5 × tDCO
ns
ps
ps
ns
ns
ns
ps
ps
ps
ns
ns
µs
Fall Time (tF) (20% to 80%)
6
DCO Period (tDCO
)
FCO Propagation Delay (tFCO
DCO Propagation Delay (tCPD
DCO to Data Delay (tDATA
)
)
7
7
)
(tSAMPLE/28) − 300
(tSAMPLE/28) − 300
(tSAMPLE/28) + 300
(tSAMPLE/28) + 300
400
7
DCO to FCO Delay (tFRAME
Data to Data Skew (tDATA-MAX − tDATA-MIN
TX_TRIG to CLK Setup Time (tSETUP
TX_TRIG to CLK Hold Time (tHOLD
Wake-Up Time (Standby)
Wake-Up Time (Power-Down)
ADC Pipeline Latency
APERTURE
)
)
)
1
1
)
2
375
16
µs
Clock cycles
Aperture Uncertainty (Jitter), tA
LO GENERATION
25°C
<1
ps rms
MLO Frequency
4LO Mode
8LO Mode
16LO Mode
RESET to MLO Setup Time (tSETUP
Full
Full
Full
Full
Full
4
8
16
1
1
40
80
160
MHz
MHz
MHz
ns
)
tMLO/2
tMLO/2
RESET to MLO Hold Time (tHOLD
)
ns
1 For a complete set of definitions and information about how these tests were completed, see the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation.
2 The clock can be adjusted via the SPI.
3 Mode III must have the RF decimator enabled, unless DVDD runs at 1.8 V and 12-bit mode is configured.
4 Mode IV must have the RF decimator enabled.
5 Measurements were made using the device soldered to FR-4 material.
6 tSAMPLE/7 is based on the number of bits (14) divided by 2 because the interface uses DDR sampling.
7 tSAMPLE/28 is based on the number of bits (14) multiplied by 2 because the delays are based on half duty cycles.
Rev. A | Page 8 of 47
Data Sheet
AD9674
ADC Timing Diagram
N – 1
AIN
tA
N
tSETUP
tHOLD
TX_TRIG+
TX_TRIG–
CLK–
tEH
tEL
CLK+
tCPD
DCO–
DCO+
tFRAME
tFCO
FCO–
FCO+
tPD
tDATA
DOUTx–
DOUTx+
MSB
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
MSB
D12
N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 17 N – 16 N – 16
Figure 2. 14-Bit Data Serial Stream (Default, RF Decimator Bypassed, Digital HPF Bypassed), One Channel per Lane Mode, FCO Mode = Word
CW Doppler Timing Diagram
tMLO
MLO–
MLO+
tHOLD
tSETUP
RESET–
RESET+
Figure 3. CW Doppler Mode Input MLO , Continuous Synchronous RESET Timing, Sampled on the Falling MLO Edge, 4LO Mode
tMLO
MLO–
MLO+
tHOLD
tSETUP
RESET–
RESET+
Figure 4. CW Doppler Mode Input MLO , Continuous Synchronous RESET Timing, Sampled on the Falling MLO Edge, 8LO Mode
Rev. A | Page 9 of 47
AD9674
Data Sheet
tMLO
MLO–
MLO+
tHOLD
tSETUP
RESET–
RESET+
Figure 5. CW Doppler Mode Input MLO , Pulse Synchronous RESET Timing, 4LO/8LO/16LO Mode
tMLO
MLO–
MLO+
tSETUP
tHOLD
RESET–
RESET+
Figure 6. CW Doppler Mode Input MLO , Pulse Asynchronous RESET Timing, 4LO/8LO/16LO Mode
Rev. A | Page 10 of 47
Data Sheet
AD9674
ABSOLUTE MAXIMUM RATINGS
Table 4.
Stresses at or above those listed under Absolute Maximum
Ratings may cause permanent damage to the product. This is a
stress rating only; functional operation of the product at these
or any other conditions above those indicated in the operational
section of this specification is not implied. Operation beyond
the maximum operating conditions for extended periods may
affect product reliability.
Parameter
Rating
AVDD1 to GND
AVDD2 to GND
DVDD to GND
DRVDD to GND
GND to GND
AVDD2 to AVDD1
AVDD1 to DRVDD
AVDD2 to DRVDD
Digital Outputs (DOUTx+, DOUTx−,
DCO+, DCO−, FCO+, FCO−) to GND
LI-x, LG-x, LO-x, LOSW-x, CWI−, CWI+,
CWQ−, CWQ+, GAIN+, GAIN−,
RESET+, RESET−, MLO+, MLO−,
GPO0, GPO1, GPO2, GPO3 to GND
−0.3 V to +2.0 V
−0.3 V to +3.9 V
−0.3 V to +2.0 V
−0.3 V to +2.0 V
−0.3 V to +0.3 V
−2.0 V to +3.9 V
−2.0 V to +2.0 V
−2.0 V to +3.9 V
−0.3 V to DRVDD + 0.3 V
THERMAL IMPEDANCE
Table 5.
Symbol Description
Value1 Unit
θJA
Junction to ambient thermal
resistance, 0.0 m/sec airflow per
JEDEC JESD51-2 (still air)
Junction to board thermal
characterization parameter, 0 m/sec
airflow per JEDEC JESD51-8 (still air)
Junction to top of package
characterization parameter, 0 m/sec
airflow per JEDEC JESD51-2 (still air)
22.0
°C/W
°C/W
°C/W
−0.3 V to AVDD2 + 0.3 V
9.2
ΨJB
ΨJT
CLK+, CLK−, TX_TRIG+, TX_TRIG−,
VREF to GND
SDIO, PDWN, STBY, SCLK, CSB, ADDRx
Operating Temperature Range
(Ambient)
−0.3 V to AVDD1 + 0.3 V
0.12
−0.3 V to DRVDD + 0.3 V
0°C to 85°C
1 Results are from simulations. The printed circuit board (PCB) is JEDEC
multilayer. Thermal performance for actual applications requires careful
inspection of the conditions in the application to determine whether they
are similar to those assumed in these calculations.
Storage Temperature Range
(Ambient)
Maximum Junction Temperature
−65°C to +150°C
150°C
ESD CAUTION
Lead Temperature (Soldering, 10 sec) 300°C
Rev. A | Page 11 of 47
AD9674
Data Sheet
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
1
2
3
4
5
6
7
8
9
10
11
12
A
B
C
LI-E
LI-F
LI-G
LI-H
VREF
RBIAS GAIN+ GAIN–
LI-A
LI-B
LI-C
LI-D
LG-E
LO-E
LG-F
LO-F
LG-G
LO-G
LG-H
LO-H
GND
GND
GND
GND
CLNA
GND
GND
GND
LG-A
LO-A
LG-B
LO-B
LG-C
LO-C
LG-D
LO-D
D
E
F
LOSW-E LOSW-F LOSW-G LOSW-H GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND LOSW-A LOSW-B LOSW-C LOSW-D
GND
AVDD1
GND
AVDD2 AVDD2 AVDD2
GND
AVDD1
GND
GND
AVDD1
GND
AVDD2 AVDD2 AVDD2
GND
AVDD1
GND
GND
AVDD1
GND
GND
DVDD
GND
GND
GND
GND
AVDD1
GND
GND
G
H
J
AVDD1
AVDD1
DVDD
CLK– TX_TRIG–
GND
GND
ADDR4 ADDR3 ADDR2 ADDR1 ADDR0
CSB
CLK+ TX_TRIG+ CWQ+
CWI+
AVDD2 MLO+ RESET– GPO3
AVDD2 MLO– RESET+ GPO2
GPO1
GPO0
PDWN
STBY
SDIO
K
L
GND
GND
CWQ–
CWI–
SCLK
DRVDD DOUTH+ DOUTG+ DOUTF+ DOUTE+ DCO+
GND DOUTH– DOUTG– DOUTF– DOUTE– DCO–
FCO+ DOUTD+ DOUTC+ DOUTB+ DOUTA+ DRVDD
FCO– DOUTD– DOUTC– DOUTB– DOUTA– GND
M
Figure 7. Pin Configuration
4
6
10
12
2
8
1
3
5
7
9
11
A
B
C
D
E
F
G
H
J
K
L
M
TOP VIEW
(Not to Scale)
Figure 8. CSP_BGA Pin Location
Rev. A | Page 12 of 47
Data Sheet
AD9674
Table 6. Pin Function Descriptions
Pin No.
Mnemonic
Description
B5, B6, B8, C5 to C8, D5 to D8, E1, E5 to
E8, E12, F2, F4, F6, F7, F9, F11, G1, G3,
G5 to G8, G10, G12, H3 to H6, J4, K1,
K2, K4, M1, M12
GND
Ground. Tie to a quiet analog ground.
F1, F3, F5, F8, F10, F12, G2, G9
G4, G11
AVDD1
DVDD
1.8 V Analog Supply.
1.4 V/1.8 V Digital Supply.
E2 to E4, E9 to E11, J6, K6
B7
AVDD2
CLNA
3.0 V Analog Supply.
LNA External Capacitor.
L1, L12
C1
D1
A1
B1
DRVDD
LO-E
LOSW-E
LI-E
1.8 V Digital Output Driver Supply.
LNA Analog Inverted Output for Channel E.
LNA Analog Switched Output for Channel E.
LNA Analog Input for Channel E.
LNA Ground for Channel E.
LG-E
C2
LO-F
LOSW-F
LI-F
LNA Analog Inverted Output for Channel F.
LNA Analog Switched Output for Channel F.
LNA Analog Input for Channel F.
LNA Ground for Channel F.
D2
A2
B2
LG-F
C3
LO-G
LOSW-G
LI-G
LNA Analog Inverted Output for Channel G.
LNA Analog Switched Output for Channel G.
LNA Analog Input for Channel G.
LNA Ground for Channel G.
D3
A3
B3
LG-G
C4
LO-H
LOSW-H
LI-H
LNA Analog Inverted Output for Channel H.
LNA Analog Switched Output for Channel H.
LNA Analog Input for Channel H.
LNA Ground for Channel H.
D4
A4
B4
LG-H
H1
J1
CLK−
CLK+
Clock Input Complement.
Clock Input True.
H2
J2
TX_TRIG−
TX_TRIG+
ADDR0
ADDR1
ADDR2
ADDR3
ADDR4
DOUTH−
DOUTH+
DOUTG−
DOUTG+
DOUTF−
DOUTF+
DOUTE−
DOUTE+
DCO−
Transmit Trigger Complement.
Transmit Trigger True.
Chip Address Bit 0.
Chip Address Bit 1.
Chip Address Bit 2.
H11
H10
H9
H8
H7
M2
L2
M3
L3
M4
L4
Chip Address Bit 3.
Chip Address Bit 4.
ADC Channel H Digital Output Complement.
ADC Channel H Digital Output True.
ADC Channel G Digital Output Complement.
ADC Channel G Digital Output True.
ADC Channel F Digital Output Complement.
ADC Channel F Digital Output True.
ADC Channel E Digital Output Complement.
ADC Channel E Digital Output True.
Digital Clock Output Complement.
Digital Clock Output True.
M5
L5
M6
L6
DCO+
M7
L7
M8
L8
M9
L9
M10
L10
M11
FCO−
FCO+
Frame Clock Digital Output Complement.
Frame Clock Digital Output True.
ADC Channel D Digital Output Complement.
ADC Channel D Digital Output True.
ADC Channel C Digital Output Complement.
ADC Channel C Digital Output True.
ADC Channel B Digital Output Complement.
ADC Channel B Digital Output True.
ADC Channel A Digital Output Complement.
DOUTD−
DOUTD+
DOUTC−
DOUTC+
DOUTB−
DOUTB+
DOUTA−
Rev. A | Page 13 of 47
AD9674
Data Sheet
Pin No.
L11
K11
J11
K12
J12
H12
B9
Mnemonic
DOUTA+
STBY
PDWN
SCLK
SDIO
CSB
LG-A
Description
ADC Channel A Digital Output True.
Standby Power-Down.
Full Power-Down.
Serial Clock.
Serial Data Input/Output.
Chip Select Bar.
LNA Ground for Channel A.
A9
D9
C9
LI-A
LOSW-A
LO-A
LG-B
LI-B
LOSW-B
LO-B
LG-C
LI-C
LOSW-C
LO-C
LNA Analog Input for Channel A.
LNA Analog Switched Output for Channel A.
LNA Analog Inverted Output for Channel A.
LNA Ground for Channel B.
LNA Analog Input for Channel B.
LNA Analog Switched Output for Channel B.
LNA Analog Inverted Output for Channel B.
LNA Ground for Channel C.
LNA Analog Input for Channel C.
LNA Analog Switched Output for Channel C.
LNA Analog Inverted Output for Channel C.
LNA Ground for Channel D.
LNA Analog Input for Channel D.
LNA Analog Switched Output for Channel D.
LNA Analog Inverted Output for Channel D.
General-Purpose Open-Drain Output 0.
General-Purpose Open-Drain Output 1.
General-Purpose Open-Drain Output 2.
General-Purpose Open-Drain Output 3.
B10
A10
D10
C10
B11
A11
D11
C11
B12
A12
D12
C12
K10
J10
K9
J9
J8
K8
K7
J7
A8
A7
A6
LG-D
LI-D
LOSW-D
LO-D
GPO0
GPO1
GPO2
GPO3
RESET−
RESET+
MLO−
MLO+
GAIN−
GAIN+
RBIAS
VREF
Synchronizing Input for LO Divide-by-M Counter Complement.
Synchronizing Input for LO Divide-by-M Counter True.
CW Doppler Multiple Local Oscillator Input Complement.
CW Doppler Multiple Local Oscillator Input True.
Gain Control Voltage Input Complement.
Gain Control Voltage Input True.
External Resistor to Set the Internal ADC Core Bias Current.
Voltage Reference Input/Output.
A5
K5
J5
K3
J3
CWI−
CWI+
CWQ−
CWQ+
CW Doppler I Output Complement.
CW Doppler I Output True.
CW Doppler Q Output Complement.
CW Doppler Q Output True.
Rev. A | Page 14 of 47
Data Sheet
AD9674
TYPICAL PERFORMANCE CHARACTERISTICS
TGC MODE
Mode I = fSAMPLE = 40 MSPS, fIN = 5 MHz, LO band mode, RS = 50 Ω, RFB = ∞ (unterminated), LNA gain = 21.6 dB, LNA bias = midhigh,
PGA gain = 27 dB, VGAIN = (GAIN+) − (GAIN−) = 1.6 V, AAF LPF cutoff = fSAMPLE/3, HPF cutoff = LPF cutoff/12 (default), RF decimator
bypassed, and digital HPF bypassed, unless otherwise noted.
2.0
25
20
15
10
5
1.5
1.0
0°C
0.5
0
25°C
85°C
–0.5
–1.0
–1.5
0
–2.0
–1.6
–1.2
–0.8
–0.4
0
0.4
0.8
1.2
1.6
V
(V)
GAIN
GAIN ERROR (dB)
Figure 12. Gain Error Histogram, VGAIN = 1.28 V
Figure 9. Gain Error vs. VGAIN
20
15
10
25
20
15
10
5
5
0
0
CHANNEL-TO-CHANNEL GAIN MATCHING (dB)
GAIN ERROR (dB)
Figure 13. Gain Matching Histogram, VGAIN = −1.2 V
Figure 10. Gain Error Histogram, VGAIN = −1.28 V
20
15
10
35
30
25
20
15
10
5
5
0
0
CHANNEL-TO-CHANNEL GAIN MATCHING (dB)
GAIN ERROR (dB)
Figure 14. Gain Matching Histogram, VGAIN = 1.2 V
Figure 11. Gain Error Histogram, VGAIN = 0 V
Rev. A | Page 15 of 47
AD9674
Data Sheet
1.4
1.2
1.0
0.8
0.6
70
68
66
64
62
60
58
56
54
52
LNA GAIN = 17.9dB
LNA GAIN = 15.6dB
LNA GAIN = 21.6dB
0.4
1
50
10
2
3
4
5
6
7
8
9
10
15
20
25
30
35
40
45
50
55
FREQUENCY (MHz)
CHANNEL GAIN (dB)
Figure 15. Short-Circuit, Input Referred Noise vs. Frequency
Figure 18. SNR vs. Channel Gain and LNA Gain,
Output Amplitude (AOUT) = −1.0 dBFS
–132
74
72
70
68
66
64
62
60
58
56
PGA GAIN = 21dB
PGA GAIN = 21dB
–134
–136
–138
–140
–142
–144
–146
PGA GAIN = 24dB
PGA GAIN = 27dB
PGA GAIN = 30dB
LNA GAIN = 21.6dB
54
–5
0
5
10
15
20
25
30
35
40
45
–5
0
5
10 15 20 25 30 35 40 45 50 55
CHANNEL GAIN (dB)
CHANNEL GAIN (dB)
Figure 16. Short-Circuit, Output Referred Noise vs. Channel Gain,
PGA Gain = 21 dB, VGAIN = 1.6 V
Figure 19. SNR vs. Channel Gain and PGA Gain,
Input Amplitude (AIN) = −45 dBm
70
0
–1
–2
–3
–4
–5
–6
–7
–8
–9
–10
SPEED MODE = I (40MSPS)
LO BAND MODE
PGA GAIN = 21dB
68
66
PGA GAIN = 24dB
64
62
60
58
56
54
52
50
PGA GAIN = 27dB
PGA GAIN = 30dB
LNA GAIN = 21.6dB
15 20
10
25
30
35
40
45
50
55
0
5
10
INPUT FREQUENCY (MHz)
15
20
CHANNEL GAIN (dB)
Figure 20. AAF Pass-Band Response, LPF Cutoff = 1 × (1/3) × fSAMPLE
HPF = LPF Cutoff/12
,
Figure 17. SNR vs. Channel Gain and PGA Gain, AOUT = −1.0 dBFS
Rev. A | Page 16 of 47
Data Sheet
AD9674
0
0
–10
LNA GAIN = 21.6dB
PGA GAIN = 27dB
MIN V , A
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
= –12.0dBFS
= –1.0dBFS
GAIN
OUT
–20
MAX V
, A
GAIN
OUT
–30
–40
–50
V
= –1.2V
GAIN
THIRD-ORDER, MIN V
GAIN
–60
THIRD-ORDER, MAX V
V
= 0V
GAIN
GAIN
–70
–80
SECOND-ORDER, MIN V
–90
GAIN
V
= +1.6V
GAIN
–100
–110
–120
SECOND-ORDER, MAX V
GAIN
2
3
4
5
6
7
8
9
10
11
–40
–35
–30
–25
–20
–15
–10
–5
0
INPUT FREQUENCY (MHz)
ADC OUTPUT LEVEL (dBFS)
Figure 21. Second-Order and Third-Order Harmonic Distortion vs. Input
Frequency, AOUT = −1.0 dBFS
Figure 24. Second-Order Harmonic Distortion vs. ADC Output Level (AOUT)
0
0
–10
–20
–30
PGA GAIN = 24dB
–10
–20
–30
–40
–50
–60
–40
–50
V
= –1.2V
GAIN
–60
V
= 0V
GAIN
–70
LNA GAIN = 17.9dB
–80
–70
LNA GAIN = 21.6dB
–90
–80
V
= +1.6V
–5
LNA GAIN = 15.6dB
GAIN
–100
–110
–120
–90
–100
10
15
20
25
30
35
40
45
50
–40
–35
–30
–25
–20
–15
–10
0
CHANNEL GAIN (dB)
ADC OUTPUT LEVEL (dBFS)
Figure 22. Second-Order Harmonic Distortion vs. Channel Gain,
OUT = −1.0 dBFS
Figure 25. Third-Order Harmonic Distortion vs. ADC Output Level (AOUT
)
A
0
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–110
–120
–130
–140
–150
–160
PGA GAIN = 24dB
LNA GAIN = 17.9dB
LNA GAIN = 21.6dB
LNA GAIN = 15.6dB
–100
10
15
20
25
30
35
40
45
100
1k
10k
100k
CHANNEL GAIN (dB)
OFFSET FREQUENCY FROM CARRIER (Hz)
Figure 23. Third-Order Harmonic Distortion vs. Channel Gain,
OUT = −1.0 dBFS
Figure 26. TGC Path Phase Noise, LNA Gain = 21.6 dB, PGA Gain = 27 dB,
GAIN = 0 V
A
V
Rev. A | Page 17 of 47
AD9674
Data Sheet
8
7
0
–10
fIN1 = 5.0MHz
fIN2 = 5.01MHz
6
5
4
3
2
FUND1 LEVEL = –1dBFS
FUND2 LEVEL = –21dBFS
–20
–30
–40
1
0
100k
–50
1M
10M
FREQUENCY (Hz)
100M
–60
V
= –1.2V
GAIN
0
–10
–20
–30
–40
–50
–60
–70
–80
–70
–80
–90
–100
–110
–120
V
= +1.6V
GAIN
V
= 0V
GAIN
–90
100k
–40
–35
–30
–25
–20
–15
–10
–5
0
1M
10M
FREQUENCY (Hz)
100M
ADC OUTPUT LEVEL (dBFS)
Figure 27. LNA Input Impedance Magnitude and Phase, Unterminated
Figure 29. IMD3 vs. ADC Output Level (AOUT)
0
7
6
5
4
3
2
1
fIN1 = 2.3MHz
fIN2 = 2.31MHz
–10
FUND1 LEVEL = –1dBFS
FUND2 LEVEL = –21dBFS
–20
R
= 50Ω
S
–30
–40
–50
–60
–70
–80
–90
–100
R
= 1000Ω
IN
R
= 50Ω
IN
R
= 300Ω
IN
15
20
25
30
35
40
45
50
0
2
4
6
8
10
12
14
16
18
20
CHANNEL GAIN (dB)
FREQUENCY (MHz)
Figure 28. IMD3 vs. Channel Gain
Figure 30. Noise Figure vs. Frequency, RS = RIN = 100 Ω, LNA Gain = 17.9 dB,
PGA Gain = 30 dB, VGAIN = 1.6 V
Rev. A | Page 18 of 47
Data Sheet
AD9674
CW DOPPLER MODE
fIN = 5 MHz, fLO = 20 MHz, 4LO mode, RS = 50 Ω, LNA gain = 21.6 dB, LNA bias = midhigh, all CW channels enabled, phase rotation = 0°.
10
9
8
7
6
5
4
3
2
1
0
165
160
155
150
145
140
135
130
0
1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
BASEBAND FREQUENCY (Hz)
0
1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
BASEBAND FREQUENCY (Hz)
Figure 31. Noise Figure vs. Baseband Frequency
Figure 32. SNR vs. Baseband Frequency, −3 dBFS LNA Input
Rev. A | Page 19 of 47
AD9674
Data Sheet
THEORY OF OPERATION
MLO–
MLO+
LO
RESET+
RESET–
CWI+
CWI–
GENERATION
R
R
LO-x
FB1
CWQ+
CWQ–
LOSW-x
FB2
T/R
SWITCH
C
S
LI-x
DOUTx+
DOUTx–
14-BIT
ADC
FILTER
DEC
SERIAL
LVDS
ATTENUATOR
–45dB TO 0dB
POST
AMP
FILTER
LNA
15.6dB,
17.9dB,
21.6dB
LG-x
C
SH
C
LG
21dB,
24dB,
27dB,
30dB
GAIN
INTERPOLATOR
TRANSDUCER
gm
GAIN+ GAIN–
Figure 33. Simplified Block Diagram of a Single Channel
Each channel of the AD9674 contains both a TGC signal path and
a CW Doppler signal path. Common to both signal paths, the
LNA provides four user adjustable input impedance termination
options for matching different probe impedances. The CW
Doppler path includes an I/Q demodulator with the programmable
phase rotation needed for analog beamforming. The TGC path
includes a differential X-AMP® VGA, an antialiasing filter, an ADC,
and a digital HPF and RF decimator. Figure 33 shows a simplified
block diagram with the external components.
The total channel gain can then be calculated as shown in
Equation 3.
Channel Gain (dB) = LNAGAIN + VGAATT + PGAGAIN
(3)
In its default condition, the LNA has a gain of 21.6 dB (12×),
and the VGA postamplifier gain is 24 dB. If the voltage on the
GAIN+ pin is 0 V and the voltage on the GAIN− pin is 1.6 V
(45.1 dB attenuation), the total gain of the channel is 0.5 dB if
the LNA input is unmatched. The channel gain is −5.5 dB if the
LNA is matched to 50 Ω (RFB = 300 Ω). However, if the voltage on
the GAIN+ pin is 1.6 V and the voltage on the GAIN− pin is 0 V
(0 dB attenuation), VGAATT is 0 dB. This results in a total gain of
45.3 dB through the TGC path if the LNA input is unmatched, or
in a total gain of 39.3 dB, if the LNA input is matched. Similarly,
if the LNA input is unmatched and has a gain of 21.6 dB (12×),
and the VGA postamplifier gain is 30 dB, the channel gain is
TGC OPERATION
The system gain is distributed as listed in Table 7.
Table 7. Channel Analog Gain Distribution
Section
Nominal Gain (dB)
1
LNA
15.6/17.9/21.6 (LNAGAIN
)
Attenuator
VGA Amplifier
Filter
−45 to 0 (VGAAT T)
21/24/27/30 (PGAGAIN
0
0
approximately 52 dB with 0 dB VGAATT
.
1
)
In addition to the analog VGA attenuation described in Equation 2,
the attenuation level can be digitally controlled in 3.5 dB increments.
Equation 3 is still valid, and the value of VGAATT is equal to the
attenuation level set in Address 0x011, Bits[7:4].
ADC
1The slashes represent the LNA and PGA gain settings that can change using
SPI registers.
Low Noise Amplifier (LNA)
Each LNA output is dc-coupled to a VGA input. The VGA consists
of an attenuator with a −45 dB to 0 dB range followed by an
amplifier with 21 dB, 24 dB, 27 dB, or 30 dB of gain. The X-AMP
gain interpolation technique results in low gain error and uniform
bandwidth; differential signal paths minimize distortion.
Good system sensitivity relies on a proprietary ultralow noise LNA
at the beginning of the signal chain, which minimizes the noise
contribution in the following VGA. Active impedance control
optimizes noise performance for applications that benefit from
input impedance matching.
The linear in dB gain (law conformance) range of the TGC path is
45 dB. The slope of the gain control interface is 14 dB/V, and the
gain control range is −1.6 V to +1.6 V. Equation 1 is the expression
for the differential voltage, VGAIN, at the gain control interface.
The LNA input, LI-x, is capacitively coupled to the source. An
on-chip bias generator establishes dc input bias voltages of
approximately 2.2 V and centers the output common-mode
levels at 1.5 V (AVDD2 divided by 2). A capacitor, CLG, of the
same value as the input coupling capacitor, CS, is connected
from LG-x to ground.
Equation 2 is the expression for the VGA attenuation, VGAATT
as a function of VGAIN
GAIN (V) = (GAIN+) − (GAIN−)
VGAATT (dB) = −14 (dB/V) × (1.6 − VGAIN
,
.
V
(1)
(2)
The LNA supports three gain settings, 21.6 dB, 17.9 dB, or 15.6 dB,
set through the SPI. Overload protection ensures quick recovery
time from large input voltages.
)
Rev. A | Page 20 of 47
Data Sheet
AD9674
Low value feedback resistors and the current driving capability
of the output stage allow the LNA to achieve a low input referred
noise voltage of 0.78 nV/√Hz (at a gain of 21.6 dB). On-chip
resistor matching results in precise single-ended gains, which are
critical for accurate impedance control. The use of a fully
differential topology and negative feedback minimizes distortion.
Low second-order harmonic distortion is particularly important
in harmonic ultrasound imaging applications.
At higher frequencies, the input capacitance of the LNA must be
considered. The user must determine the level of matching
accuracy and adjust RFB accordingly.
RFB is the resulting impedance of the RFB1 and RFB2 combination (see
Figure 33). Using Address 0x02C in the SPI memory, the AD9674
can be programmed for four impedance matching options: three
active terminations and one unterminated option. Table 8 shows an
example of how to select RFB1 and RFB2 for RIN = 66 Ω, 100 Ω, and
200 Ω input impedances for an LNA gain = 21.6 dB (12×).
Active Impedance Matching
The LNA consists of a single-ended voltage gain amplifier with
differential outputs; the negative output is externally available on
two output pins (LO-x and LOSW-x) that are controlled via
internal switches. This configuration allows active input impedance
synthesis of three different impedance values (and an unterminated
value) by connecting up to two external resistances in parallel
and controlling the internal switch states via the SPI. For example,
with a fixed gain of 8× (17.9 dB), an active input termination is
synthesized by connecting a feedback resistor between the negative
output pin, LO-x, and the positive input pin, LI-x. This well-known
technique is used for interfacing multiple probe impedances to a
single system. The input resistance calculation is shown in
Equation 4.
Table 8. Active Termination Example for LNA Gain = 21.6 dB,
RFB1 = 650 Ω, and RFB2 = 1350 Ω
Reg. 0x02C,
Bits[1:0]
LO-x
LOSW-x
RIN (Ω)
RS (Ω) Switch Switch
RFB (Ω)
RFB1
RFB1||RFB2
RFB2
(Eq. 4)
100
66
200
∞
00 (default)
100
50
200
N/A1
On
On
Off
Off
Off
On
On
Off
01
10
11
∞
1 N/A means not applicable.
The bandwidth (BW) of the LNA is greater than 80 MHz. Ultimately,
the BW of the LNA limits the accuracy of the synthesized RIN. RIN
=
RS up to approximately 200 Ω. The best match is between 100 kHz
and 10 MHz where the lower frequency limit is determined by
the size of the ac coupling capacitors and the upper limit is
determined by the LNA BW. Furthermore, the input capacitance
and RS limit the BW at higher frequencies. Figure 34 shows input
resistance (RIN) vs. frequency for various RFB values.
1k
(RFB1 +20 Ω)||(RFB2 +20 Ω)+30 Ω
(4)
RIN
=
A
1+
2
where A/2 is the single-ended gain or the gain from the LI-x
inputs to the LO-x outputs, RFB1 and RFB2 are the external feedback
resistors, the 20 Ω is the internal switch on resistance, and the 30 Ω
is an internal series resistance common to the two internal
switches. RFB can equal to RFB1, RFB2, or (RFB1 + 20 Ω)||(RFB2 + 20 Ω)
depending on the connection status of the internal switches.
R
= 500Ω, R = 2kΩ
FB
S
R
R
= 200Ω, R = 800Ω
S
FB
= 100Ω, R = 400Ω, C = 20pF
Because the amplifier has a gain of 8× from its input to its
differential output, it is important to note that the gain, A/2,
is the gain from the LI-x pin to the LO-x pin, and that it is 6 dB
less than the gain of the amplifier, or 12.1 dB (4×). The input
resistance is reduced by an internal bias resistor of 6 kΩ in parallel
with the source resistance connected to the LI-x pin and with the
LG-x pin ac grounded. Equation 5 can be used to calculate the
required RFB for a desired RIN, even for higher values of RIN.
S
FB
SH
100
R
= 50Ω, R = 200Ω, C = 70pF
FB SH
S
10
100k
1M
10M
100M
FREQUENCY (Hz)
(RFB1 + 20 Ω)||(RFB2 + 20 Ω) + 30 Ω
Figure 34. Input Resistance (RIN) vs. Frequency for Various RFB Values
(Effects of RS and CSH Are Also Shown)
(5)
RIN
=
||6 k Ω
A
2
1+
For larger RIN values, parasitic capacitance starts rolling off the
signal BW before the LNA can produce peaking. CSH further
degrades the match; therefore, do not use CSH for values of RIN
that are greater than 100 Ω (see Figure 34).
For example, to set RIN to 200 Ω with a single-ended LNA gain of
12.1 dB (4×), the value of RFB from Equation 4 must be 950 Ω
while the switch for RFB2 is open. If the more accurate equation
(Equation 5) is used to calculate RIN, the value is then 194 Ω
instead of 200 Ω, resulting in a gain error of less than 0.27 dB.
Some factors, such as the presence of a dynamic source resistance,
may influence the absolute gain accuracy more significantly.
Rev. A | Page 21 of 47
AD9674
Data Sheet
Table 9 lists the recommended values for RFB and CSH in terms
of RIN. CFB is needed in series with RFB because the dc levels at the
LO-x pin and the LI-x pin are unequal.
Figure 36 shows the noise figure as it relates to RS for various
values of RIN, which is helpful for design purposes.
8
R
R
R
R
= 50Ω
= 75Ω
= 100Ω
= 200Ω
IN
IN
IN
IN
7
6
5
4
3
2
1
0
Table 9. Active Termination External Component Values
LNA Gain (dB)
RIN (Ω)
RFB (Ω)
Minimum CSH (pF)
UNTERMINATED
15.6
50
150
90
17.9
50
200
70
21.6
50
300
50
15.6
17.9
21.6
15.6
17.9
21.6
100
100
100
200
200
200
350
450
650
750
950
1350
30
20
10
Not applicable
Not applicable
Not applicable
10
100
(Ω)
1k
R
S
Figure 36. Noise Figure vs. RS for Various Fixed Values of RIN
Active Termination Matched Inputs, VGAIN = 1.6 V
,
LNA Noise
The short-circuit noise voltage (input referred noise) is an important
limit on system performance. The short-circuit noise voltage for
the LNA is 0.78 nV/√Hz at a gain of 21.6 dB, including the VGA
noise at a VGA postamplifier gain of 27 dB. These measurements,
which were taken without a feedback resistor, provide the basis for
calculating the input noise and noise figure (NF) performance.
CLNA Connection
CLNA (Ball B7) must have a 1 nF capacitor attached to AVDD2.
DC Offset Correction/High-Pass Filter
The AD9674 LNA architecture is designed to correct for dc offset
voltages that can develop on the external CS capacitor due to
leakage of the transmit/receive switch during ultrasound transmit
cycles. The dc offset correction, as shown in Figure 37, provides
a feedback mechanism to the LG-x input of the LNA to correct
for this dc voltage.
Figure 35 and Figure 36 are simulations of noise figure vs. RS results
with different input configurations and an input referred noise
voltage of 2.5 nV/√Hz for the VGA. The unterminated (RFB = ∞)
operation exhibits the lowest equivalent input noise and noise
figure. Figure 36 shows the noise figure vs. the source resistance
rising at low RS, where the LNA voltage noise is large compared
with the source noise, and at high RS due to the noise contribution
from RFB. The lowest NF is achieved when RS matches RIN.
AD9674
R
R
FB1
LO-x
C
FB
LOSW-x
FB2
T/R
SWITCH
C
S
Figure 35 shows the relative noise figure performance. With an LNA
gain of 21.6 dB, the input impedance is swept with RS to preserve
the match at each point. The noise figures for a source impedance
of 50 Ω are 7 dB, 4 dB, and 2.5 dB for the shunt termination, active
termination, and unterminated configurations, respectively. The
LI-x
LNA
LG-x
C
SH
C
15.6dB,
17.9dB,
21.6dB
LG
TRANSDUCER
gm
noise figures for 200 Ω are 4.5 dB, 1.7 dB, and 1 dB, respectively.
12.0
DC OFFSET
CORRECTION
10.5
9.0
Figure 37. Simplified LNA Input Configuration
7.5
SHUNT TERMINATION
6.0
4.5
3.0
ACTIVE TERMINATION
UNTERMINATED
1.5
0
10
100
(Ω)
1k
R
S
Figure 35. Noise Figure vs. RS for Shunt Termination, Active
Termination Matched and Unterminated Inputs, VGAIN = 1.6 V
Rev. A | Page 22 of 47
Data Sheet
AD9674
The feedback acts as a high-pass filter providing dynamic correction
of the dc offset. The cutoff frequency of the high-pass filter response
is dependent on the value of the CLG capacitor, the gain of the
LNA (LNAGAIN), and the gm of the feedback transconductance
amplifier. The gm value is programmed in Address 0x120, Bits[4:3].
It is required that CS be equal to CLG for proper operation.
The differential input pins, GAIN+ and GAIN−, can interface
to an amplifier, as shown in Figure 38. Decouple and drive the
GAIN+ and GAIN− pins to accommodate a 3.2 V full-scale input.
AVDD2
249Ω
AD9674
±0.8V DC
AT 0.8V CM
31.3kΩ
±1.6V
249Ω
100Ω
GAIN+
GAIN–
0.8V CM
0.01µF
100Ω
ADA4938-1/
ADA4938-2
Table 10. High-Pass Filter Cutoff Frequency, fHP, for CLG = 10 nF
249Ω
10kΩ
±0.8V DC
AT 0.8V CM
Addr.
0x120[4:3]
LNAGAIN
gm (mS) 15.6 dB
=
LNAGAIN
17.9 dB
=
LNAGAIN
21.6 dB
=
0.01µF
249Ω
00 (default)
0.5 mS
1.0 mS
1.5 mS
2.0 mS
41 kHz
83 kHz
133 kHz
167 kHz
55 kHz
83 kHz
01
10
11
110 kHz
178 kHz
220 kHz
167 kHz
267 kHz
330 kHz
Figure 38. Differential GAIN Pin Configuration
The analog gain control can be disabled and the attenuator can be
controlled digitally using Address 0x011, Bits[7:4]. The control
range is 45 dB, and the step size is 3.5 dB.
For other values of CLG, the high-pass filter cutoff frequency can
be determined by scaling the values from Table 10 or by calculating
the value based on CLG, LNAGAIN, and gm, as shown in Equation 6.
VGA Noise
In a typical application, a VGA compresses a wide dynamic
range input signal to within the input span of an ADC. The
input referred noise of the LNA limits the minimum resolvable
input signal, whereas the output referred noise, which depends
primarily on the VGA, limits the maximum instantaneous dynamic
range that can be processed at any one particular gain control
voltage. This latter limit is set in accordance with the total noise
floor of the ADC.
10 nF
1
2× π
gm
f
HP (CLG ) =
× LNAGAIN
×
= fHP (Table 10)×
(6)
CLG
CLG
Variable Gain Amplifier (VGA)
The differential X-AMP VGA provides precise input attenuation
and interpolation. It has a low input referred noise of 2.5 nV/√Hz
and excellent gain linearity. The VGA is driven by a fully differential
input signal from the LNA. The X-AMP architecture produces a
linear in dB gain law conformance and low distortion levels,
deviating only 0.5 dB or less from the ideal. The gain slope is
monotonic with respect to the control voltage and is stable with
variations in process, temperature, and supply. The resulting total
gain range is 45 dB, allowing range loss at the endpoints.
The output referred noise is a flat 40 nV/√Hz (postamplifier
gain = 24 dB) over most of the gain range because it is dominated
by the fixed output referred noise of the VGA. At the high end of
the gain control range, the noise of the LNA and the source prevail.
The input referred noise reaches its minimum value near the
maximum gain control voltage, where the input referred
contribution of the VGA is miniscule.
The X-AMP inputs are part of a programmable gain amplifier
(PGA) that completes the VGA. The PGA in the VGA can be
programmed to a gain of 21 dB, 24 dB, 27 dB, or 30 dB, allowing
optimization of the channel gain for different imaging modes
in the ultrasound system. The VGA bandwidth is greater than
100 MHz. The input stage is designed to ensure excellent frequency
response uniformity across the gain setting. For TGC mode, the
design of the input stage minimizes time delay variation across the
gain range.
At lower gains, the input referred noise and, therefore, the noise
figure increase as the gain decreases. The instantaneous dynamic
range of the system is not lost, however, because the input capacity
increases as the input referred noise increases. The contribution of
the ADC noise floor has the same dependence. The important
relationship is the magnitude of the VGA output noise floor
relative to that of the ADC.
Gain control noise is a concern in very low noise applications.
Thermal noise in the gain control interface can modulate the
channel gain. The resulting noise is proportional to the output
signal level and is usually evident only when a large signal is
present. Take care to minimize noise impinging at the GAIN
inputs. An external RC filter can be used to remove VGAIN source
noise. The filter bandwidth must be sufficient to accommodate the
desired control bandwidth and attenuate unwanted switching noise
from the external digital-to-analog converters used to drive the
gain control.
Gain Control
The analog gain control interface, GAIN , is a differential input.
V
GAIN varies the gain of all VGAs through the interpolator by
selecting the appropriate input stages connected to the input
attenuator. The nominal VGAIN range is 14 dB/V from −1.6 V to
+1.6 V, with the best gain linearity from approximately −1.44 V
to +1.44 V, where the error is typically less than 0.5 dB. For VGAIN
voltages greater than +1.44 V and less than −1.44 V, the error
increases. The value of GAIN can exceed the supply voltage by
1 V without gain foldover.
The AD9674 can bypass the GAIN inputs and control the gain
of the attenuator digitally (see the Gain Control section). This
mode removes any external noise contributions when active gain
control is not needed.
The gain control response time is less than 750 ns to settle
within 10% of the final value for a change from minimum to
maximum gain.
Rev. A | Page 23 of 47
AD9674
Data Sheet
Antialiasing Filter (AAF)
default −3 dB low-pass filter cutoff is 1/3, 1/4.5, or 1/6 of the ADC
sample clock rate. The cutoff can be scaled to 0.75, 0.8, 0.9, 1.0,
1.13, 1.25, or 1.45 times this frequency using Address 0x00F. The
cutoff tolerance ( 10%) is maintained from 8 MHz to 18 MHz
for low band mode or 13.5 MHz to 30 MHz for high band mode.
The filter that the signal reaches prior to the ADC is used to
reject dc signals and to band limit the signal for antialiasing.
The antialiasing filter is a combination of a single-pole high-pass
filter and a second-order low-pass filter. The high-pass filter
can be configured as a ratio of the low-pass filter cutoff
frequency. This is selectable using Address 0x02B, Bits[1:0].
Table 11 and Table 12 calculate the valid SPI-selectable low-pass
filter settings and the expected cutoff frequencies for low band
mode and high band mode at the minimum and the maximum
sample frequency in each speed mode.
The filter uses on-chip tuning to trim the capacitors and set the
desired low-pass cutoff frequency and reduce variations. The
Table 11. SPI-Selectable Low-Pass Filter Cutoff Options for Low Band Mode at Example Sampling Frequencies
Sampling Frequency (MHz)
Address
0x00F[7:3] Frequency (MHz)
LPF Cutoff
20.5
40
65
80
125
0 0000
0 0001
0 0010
0 0011
0 0100
0 0101
0 0110
0 1000
0 1001
0 1010
0 1011
0 1100
0 1101
0 1110
1 0000
1 0001
1 0010
1 0011
1 0100
1 0101
1 0110
1.45 × (1/3) × fSAMPLE
1.25 × (1/3) × fSAMPLE
1.13 × (1/3) × fSAMPLE
1.0 × (1/3) × fSAMPLE
0.9 × (1/3) × fSAMPLE
0.8 × (1/3) × fSAMPLE
0.75 × (1/3) × fSAMPLE
9.91
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
8.54
16.67
15.00
13.33
12.00
10.67
10.00
12.89
11.11
10.00
8.89
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
17.33
16.25
20.94
18.06
16.25
14.44
13.00
11.56
10.83
15.71
13.54
12.19
10.83
9.75
Out of tunable
filter range
16.82
1.45 × (1/4.5) × fSAMPLE Out of tunable
filter range
1.25 × (1/4.5) × fSAMPLE Out of tunable
filter range
1.13 × (1/4.5) × fSAMPLE Out of tunable
filter range
1.0 × (1/4.5) × fSAMPLE Out of tunable
filter range
0.9 × (1/4.5) × fSAMPLE Out of tunable
filter range
0.8 × (1/4.5) × fSAMPLE Out of tunable
filter range
0.75 × (1/4.5) × fSAMPLE Out of tunable
filter range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
17.78
8.00
16.00
14.22
13.33
Out of tunable
filter range
Out of tunable
filter range
17.50
1.45 × (1/6) × fSAMPLE
1.25 × (1/6) × fSAMPLE
1.13 × (1/6) × fSAMPLE
1.0 × (1/6) × fSAMPLE
0.9 × (1/6) × fSAMPLE
0.8 × (1/6) × fSAMPLE
0.75 × (1/6) × fSAMPLE
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
9.67
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
Out of tunable filter
range
8.33
16.67
15.00
13.33
12.00
10.67
10.00
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable filter
range
16.67
8.67
Out of tunable
filter range
8.13
15.63
Rev. A | Page 24 of 47
Data Sheet
AD9674
Table 12. SPI-Selectable Low-Pass Filter Cutoff Options for High Band Mode at Example Sampling Frequencies
Sampling Frequency (MHz)
Address
LPF Cutoff
0x00F[7:3]
Frequency (MHz)
20.5
40
65
80
125
0 0000
0 0001
0 0010
0 0011
0 0100
0 0101
0 0110
0 1000
0 1001
0 1010
0 1011
0 1100
0 1101
0 1110
1 0000
1 0001
1 0010
1 0011
1 0100
1 0101
1 0110
1.45 × (1/3) × fSAMPLE
1.25 × (1/3) × fSAMPLE
1.13 × (1/3) × fSAMPLE
1.0 × (1/3) × fSAMPLE
0.9 × (1/3) × fSAMPLE
0.8 × (1/3) × fSAMPLE
0.75 × (1/3) × fSAMPLE
1.45 × (1/4.5) × fSAMPLE
1.25 × (1/4.5) × fSAMPLE
1.13 × (1/4.5) × fSAMPLE
1.0 × (1/4.5) × fSAMPLE
0.9 × (1/4.5) × fSAMPLE
0.8 × (1/4.5) × fSAMPLE
0.75 × (1/4.5) × fSAMPLE
1.45 × (1/6) × fSAMPLE
1.25 × (1/6) × fSAMPLE
1.13 × (1/6) × fSAMPLE
1.0 × (1/6) × fSAMPLE
0.9 × (1/6) × fSAMPLE
0.8 × (1/6) × fSAMPLE
0.75 × (1/6) × fSAMPLE
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
19.33
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
16.67
15.00
27.08
24.38
21.67
19.50
17.33
16.25
20.94
18.06
16.25
14.44
30.00
26.67
24.00
21.33
20.00
25.78
22.22
20.00
17.78
16.00
14.22
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
27.78
25.00
22.22
20.83
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
15.71
19.33
16.67
15.00
Out of tunable
filter range
13.54
26.04
23.44
20.83
18.75
16.67
15.63
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Out of tunable
filter range
Rev. A | Page 25 of 47
AD9674
Data Sheet
Tuning is normally off to avoid changing the capacitor settings
during critical times. The tuning circuit is enabled through the
SPI. It is disabled automatically after 512 cycles of the ADC sample
clock. Initializing the tuning of the filter must be performed
after initial power-up and after reprogramming of the filter cutoff
scaling or the ADC sample rate. The tuning is initiated using
Address 0x02B, Bit 6.
Figure 39 shows the preferred method for clocking the AD9674. A
low jitter clock source, such as the Valpey Fisher oscillator, VFAC3-
BHL-50 MHz, is converted from a single-ended configuration
to a differential configuration using an RF transformer.
The back to back Schottky diodes across the secondary transformer
limit clock excursions into the AD9674 to approximately 0.8 V p-p
differential. These diodes help prevent large voltage swings of the
clock from feeding through to other portions of the AD9674, and
they preserve the fast rise and fall times of the signal, which is
critical to low jitter performance.
Four SPI-programmable settings allow users to vary the high-
pass filter cutoff frequency as a function of the low-pass cutoff
frequency. Two examples are shown in Table 13: an 8 MHz low-
pass cutoff frequency and an 18 MHz low-pass cutoff frequency. In
both cases, as the ratio decreases, the amount of rejection on the
low end frequencies increases. Therefore, making the entire AAF
frequency pass band narrow can reduce low frequency noise or
maximize the dynamic range for harmonic processing.
3.3V
®
MINI-CIRCUITS
ADT1-1WT, 1:1Z
0.1µF
0.1µF
0.1µF
XFMR
CLK+
OUT
100Ω
50Ω
ADC
VFAC3
CLK–
SCHOTTKY
DIODES:
HSM2812
0.1µF
Table 13. High-Pass Filter Cutoff Options
High-Pass Cutoff Frequency
Addr. 0x02B[1:0]
High-Pass
Filter Cutoff
Figure 39. Transformer-Coupled Differential Clock
Low-Pass
Low-Pass
Ratio1 Cutoff = 8 MHz Cutoff = 18 MHz
If a low jitter clock is available, another option is to ac couple a
differential positive emitter coupled logic (PECL) signal to the
sample clock input pins, as shown in Figure 40. Analog
Devices,Inc., offers a family of clock drivers with excellent jitter
performance,including the AD9516-0, AD9516-1, AD9516-2,
AD9516-3, and AD9516-5 (these five devices are represented by
AD9516-x in Figure 40, Figure 41, and Figure 42), as well as the
AD9524.
00 (default)
12
9
6
670 kHz
890 kHz
1.33 MHz
2.67 MHz
1.5 MHz
2.0 MHz
3.0 MHz
6.0 MHz
01
10
11
3
1 Ratio means low-pass filter cutoff frequency/high-pass filter cutoff frequency.
AAF/VGA Test Mode
For debugging and testing, there is a bypass switch to view the
AAF output on the GPO2 and GPO3 pins. This mode can be
enabled via Address 0x109, Bit 4. The differential AAF output
allows only one channel to be accessed at a time. The dc output
voltage is 1.5 V (or AVDD2/2), and the maximum ac output
voltage is 2 V p-p.
3.3V
AD9516-x OR AD9524
VFAC3
OUT
0.1µF
0.1µF
CLK+
CLK
PECL DRIVER
CLK
50Ω*
0.1µF
100Ω
ADC
0.1µF
CLK–
240Ω
240Ω
ADC
The AD9674 uses a pipelined ADC architecture. The quantized
output from each stage is combined into a 14-bit result in the
digital correction logic. The pipelined architecture permits the
first stage to operate on a new input sample and the remaining
stages to operate on the preceding samples. Sampling occurs on
the rising edge of the clock.
*50Ω RESISTOR IS OPTIONAL.
Figure 40. Differential PECL Sample Clock
A third option is to ac couple a differential LVDS signal to the
sample clock input pins, as shown in Figure 41.
3.3V
AD9516-x OR AD9524
VFAC3
OUT
0.1µF
0.1µF
The output staging block aligns the data, corrects errors, and
passes the data to the output buffers. The data is then serialized
and aligned to the frame and output clocks.
CLK+
CLK
LVDS DRIVER
CLK
50Ω*
0.1µF
100Ω
ADC
0.1µF
CLK–
Clock Input Considerations
For optimum performance, clock the AD9674 sample clock inputs
(CLK+ and CLK−) with a differential signal. This signal is typically
ac-coupled into the CLK+ and CLK− pins via a transformer or
capacitors. These pins are biased internally and require no
additional bias.
*50Ω RESISTOR IS OPTIONAL.
Figure 41. Differential LVDS Sample Clock
In some applications, it is acceptable to drive the sample clock
inputs with a single-ended CMOS signal. In such applications,
drive CLK+ directly from a CMOS gate, and bypass the CLK− pin
to ground with a 0.1 µF capacitor (see Figure 42).
Rev. A | Page 26 of 47
Data Sheet
AD9674
3.3V
130
120
110
100
90
RMS CLOCK JITTER REQUIREMENT
AD9516-x OR AD9524
OPTIONAL
0.1µF
VFAC3
OUT
CLK
0.1µF
50Ω*
100Ω
CLK+
CMOS DRIVER
CLK
16 BITS
ADC
14 BITS
12 BITS
0.1µF
80
CLK–
0.1µF
70
10 BITS
*50Ω RESISTOR IS OPTIONAL.
60
0.125ps
8 BITS
0.25ps
Figure 42. Single-Ended 1.8 V CMOS Sample Clock
50
0.5ps
1.0ps
2.0ps
Clock Duty Cycle Considerations
40
30
Typical high speed ADCs use both clock edges to generate a
variety of internal timing signals. As a result, these ADCs can be
sensitive to the clock duty cycle. Commonly, a 5% tolerance is
required on the clock duty cycle to maintain dynamic performance
characteristics. The AD9674 contains a duty cycle stabilizer (DCS)
that retimes the nonsampling edge, providing an internal clock
signal with a nominal 50% duty cycle. This feature allows a wide
range of clock input duty cycles without affecting the performance
of the AD9674. When the DCS is on, noise and distortion
performance are nearly flat for a wide range of duty cycles.
However, some applications may require the DCS function to
be off. When the DCS function is off, the dynamic range
performance can be affected.
1
10
100
1000
ANALOG INPUT FREQUENCY (MHz)
Figure 43. Ideal SNR vs. Analog Input Frequency and Jitter
Power Dissipation and Power-Down Mode
The power dissipated by the AD9674 is proportional to its sample
rate. The digital power dissipation does not vary significantly
because it is determined primarily by the DRVDD supply and
the bias current of the LVDS output drivers. The AD9674 features
scalable LNA bias currents (see Table 25, Address 0x012). The
default LNA bias current settings are midhigh.
By asserting the PDWN pin high, the AD9674 is placed into
power-down mode. In this state, the device dissipates at a
maximum of 30 mW. During power-down, the LVDS output
drivers are placed into a high impedance state. The AD9674
returns to normal operating mode when the PDWN pin is pulled
low. This pin is only 1.8 V tolerant. To drive the PDWN pin from a
3.3 V logic level, insert a 1 kΩ resistor in series with this pin to
limit the current.
The duty cycle stabilizer uses a delay-locked loop (DLL) to create
the nonsampling edge. As a result, any changes to the sampling
frequency require approximately eight clock cycles to allow the
DLL to acquire and lock to the new rate.
Clock Jitter Considerations
High speed, high resolution ADCs are sensitive to the quality of the
clock input. The degradation in SNR at a given input frequency (fA)
due only to aperture jitter (tJ) can be calculated as follows:
By asserting the STBY pin high, the AD9674 is placed in standby
mode. In this state, the device typically dissipates 630 m W. Du r i ng
standby, the entire device, except the internal references, powers
down. The LVDS output drivers are placed into a high impedance
state. This mode is well suited for applications that require power
savings because it allows the device to be powered down when
not in use and then to be quickly powered up. In addition, the
time to power up the device is greatly reduced. The AD9674
returns to normal operating mode when the STBY pin is pulled
low. This pin is only 1.8 V tolerant. To drive the STBY pin from
a 3.3 V logic level, insert a 1 kΩ resistor in series with this pin to
limit the current.
SNR Degradation = 20 × log 10(1/2 × π × fA × tJ)
(7)
In Equation 7, the rms aperture jitter represents the root mean
square of all jitter sources, including the clock input, analog
input signal, and ADC aperture jitter (see Figure 43).
Treat the clock input as an analog signal when aperture jitter may
affect the dynamic range of the AD9674. Separate power supplies
for clock drivers from the ADC output driver supplies to avoid
modulating the clock signal with digital noise. Low jitter, crystal
controlled oscillators, such as the Valpey Fisher VFAC3 series,
make the best clock sources. When the clock is generated from
another type of source (by gating, dividing, or other methods),
retime it by the original clock during the last step.
For more information on how jitter performance relates to ADCs,
refer to the AN-501 Application Note and AN-756 Application Note.
Rev. A | Page 27 of 47
AD9674
Data Sheet
In power-down mode, low power dissipation is achieved by
shutting down the reference, reference buffer, phase-locked loop
(PLL), and biasing networks. The decoupling capacitors on VREF
are discharged when entering power-down mode and must be
recharged when returning to normal operation. As a result, the
wake-up time is related to the time spent in power-down mode:
shorter cycles result in proportionally shorter wake-up times. To
restore the device to full operation, approximately 375 µs is
required when using the recommended 1 µF and 0.1 µF dec-
oupling capacitors on the VREF pin and the 0.01 µF decoupling
capacitors on the GAIN pins. Most of this time is dependent on
gain decoupling; higher value decoupling capacitors on the
GAIN pins result in longer wake-up times.
POWER_STOP
(PROFILE SPECIFIC)
TX_TRIG±
POWER_START
(PROFILE SPECIFIC)
DIGITAL
POWER
ANALOG
POWER
POWER_SETUP
(SPI SET)
Figure 44. Power Sequencing
Digital Outputs and Timing
The AD9674 differential outputs conform to the ANSI-644
LVDS standard on default power-up. This setting can be
changed to a low power, reduced signal option similar to the
IEEE 1596.3 standard via the SPI using Address 0x015, Bit 7.
This LVDS standard can further reduce the overall power
dissipation of the device by approximately 36 mW.
Other power-down options are available when using the SPI port
interface. The user can individually power down each channel or
place the entire device into standby mode. When fast wake-up
times are required, standby mode allows the user to keep the
internal PLL powered up. The wake-up time is slightly dependent
on gain. To achieve a 2 µs wake-up time when the device is in
standby mode, apply 0.8 V to the GAIN pins.
The LVDS driver current is derived on chip and sets the output
current at each output equal to a nominal 3.5 mA. A 100 Ω
differential termination resistor placed at the LVDS receiver
inputs results in a nominal 350 mV swing at the receiver.
Power and Ground Connection Recommendations
When connecting power to the AD9674, use two separate 1.8 V
supplies: one for analog (AVDD1) and one for digital (DRVDD).
When only one 1.8 V supply is available, route it to the AVDD1
pin first, tap it off, and isolate it with a ferrite bead or a filter
choke preceded by decoupling capacitors for the DRVDD pin.
The AD9674 LVDS outputs facilitate interfacing with LVDS
receivers in custom ASICs and FPGAs that have LVDS capability
for superior switching performance in noisy environments. Single
point to point network topologies are recommended with a 100 Ω
termination resistor placed as close to the receiver as possible.
No far-end receiver termination and poor differential trace routing
may result in timing errors. The trace length must be no longer
than 24 inches; keep the differential output traces close together
and at equal lengths.
The DVDD pin can be tied to the 1.8 V DRVDD supply. When
this is done, route the DVDD supply first, tap it off, and isolate it
with a ferrite bead or filter choke preceded by decoupling
capacitors for the DRVDD pin. It is not recommended to use the
same supply for AVDD1, DVDD, and DRVDD to avoid noise
issues. For compatibility with the AD9674 or for lower power
operation, the DVDD pin can be tied to 1.4 V.
Figure 45 and Figure 46 show an example of the LVDS output
using the ANSI-644 standard (default) data eye and a time interval
error (TIE) jitter histogram with trace lengths of less than 24 inches
on standard FR-4 material. Figure 47 and Figure 48 show an
example of the trace lengths exceeding 24 inches on standard
FR-4 material. Notice that the TIE jitter histogram reflects the
decrease of the data eye opening as the edge deviates from the
ideal position. Therefore, the user must determine whether the
waveforms meet the timing budget of the design when the trace
lengths exceed 24 inches.
To cover both high and low frequencies, use several decoupling
capacitors on all supplies. Locate these capacitors close to the
point of entry at the PCB level and close to the device, with
minimal trace lengths.
When using the AD9674, a single PCB ground plane is sufficient.
With proper decoupling and smart partitioning of the analog,
digital, and clock sections of the PCB, optimum performance is
easily achievable.
Advanced Power Control
For an ultrasound system, not all channels are needed during all
scanning periods. The POWER_START and POWER_STOP
values in the vector profile can be used to delay the channel
startup and turn the channel off after a certain number of samples.
These counters are relative to TX_TRIG . The analog circuitry
must power up before the digital circuitry. The analog circuitry
must power up (POWER_SETUP) before POWER_START is
set up in Register 0x112 (see Table 25).
Rev. A | Page 28 of 47
Data Sheet
AD9674
80
70
60
50
40
30
20
10
EYE: ALL BITS
ULS: 11197/11197
400
300
200
100
0
–100
–200
–300
–400
0
–300ps
–200ps
–100ps
0ps
100ps
200ps
300ps
–1.5ns
–1.0ns –0.5ns
0ns
0.5ns
1.0ns
1.5ns
Figure 48. TIE Jitter Histogram for LVDS Outputs in ANSI-644 Mode with
Trace Lengths of Greater Than 24 Inches on Standard FR-4
Figure 45. Data Eye for LVDS Outputs in ANSI-644 Mode with Trace Lengths
of Less Than 24 Inches on Standard FR-4
Additional SPI options let the user further increase the internal
current of all eight outputs to drive longer trace lengths. Even
though this produces sharper rise and fall times on the data edges,
increasing the internal current is less prone to bit errors and
improves frequency distribution. The power dissipation of the
DRVDD supply increases when this option is used.
70
60
50
40
30
20
10
0
In applications that require increased drive current, Address 0x015
allows the user to adjust the drivers from 2 mA to 3.72 mA. Note
that this feature requires Bit 3 of Address 0x015 to be set to 1. The
drive current can be adjusted for both ANSI-644 and IEEE 1596.3
(low power) mode. See Table 25 for more details.
The format of the output data is twos complement by default.
Table 14 provides an example of the output coding format. To
change the output data format to twos complement, see the
Memory Map section.
–150ps
–100ps
–50ps
0ps
50ps
100ps
150ps
Figure 46. TIE Jitter Histogram for LVDS Outputs in ANSI-644 Mode with
Trace Lengths of Less Than 24 Inches on Standard FR-4
Table 14. Digital Output Coding with RF Decimator Bypassed,
Digital HPF Bypassed
EYE: ALL BITS
ULS: 11199/11199
400
300
(VIN+) − (VIN−),
Digital Output Mode: Twos
Code Input Span = 2 V p-p (V) Complement (D13 to D0)
200
16384 +1.00
01 1111 1111 1111
00 0000 0000 0000
11 1111 1111 1111
10 0000 0000 0000
100
8192
8191
0
0.00
−0.000488
−1.00
0
–100
–200
–300
–400
Digital data from each channel is serialized based on the number
of lanes that are enabled (see Table 25). The maximum data rate
for each serial output lane is 1 Gbps. For one channel per lane with
a 14-bit data stream and ADC sample clock of 70 MHz, the output
data rate is 980 Mbps (14 bits × 70 MHz = 980 Mbps) with the
RF decimator bypassed, and digital HPF bypassed. For higher
sample rates, enabling the RF decimator is required.
–1.5ns
–1.0ns –0.5ns
0ns
0.5ns
1.0ns
1.5ns
Figure 47. Data Eye for LVDS Outputs in ANSI-644 Mode with Trace Lengths
of Greater Than 24 Inches on Standard FR-4
Two output clocks are provided to assist in capturing data from
the AD9674. The digital clock outputs (DCO ) are used to clock
the output data and are equal to seven times the sampling clock
rate in 14-bit mode with the RF decimator bypassed and digital
HPF bypassed.
Rev. A | Page 29 of 47
AD9674
Data Sheet
Data is clocked out of the AD9674 and must be captured on the
rising and falling edges of DCO , which support double data
rate (DDR) capturing. The frame clock outputs (FCO ) signal
the start of a new output byte and are equal to the sampling
clock rate.
Table 15. PN Sequence Initial Values
Initial
Value
First Three Output Samples
(MSB First, 16-Bit)
Sequence
PN Sequence Short
PN Sequence Long
0x092
0x003
0x496F, 0xC9A9, 0x980C
0xFF5C, 0x0029, 0xB80A
A 12-, 14-, or 16-bit serial stream can also be initiated from
Address 0x021, Bits[1:0]. The user can implement different serial
streams and test device compatibility with lower and higher
resolution systems using these modes.
See the Memory Map section for information on how to change
these additional digital output timing features through the SPI.
SDIO Pin
The SDIO pin is required to operate the SPI. The pin has an
internal 30 kΩ pull-down resistor that pulls this pin low and is only
1.8 V tolerant. If applications require that this pin be driven
from a 3.3 V logic level, insert a 1 kΩ resistor in series with this
pin to limit the current.
When using the SPI, all the data outputs can also invert from
their nominal state by setting Bit 2 in the output mode register
(Address 0x014). This feature is not to be confused with inverting
the serial stream to an LSB first mode. In default mode, as shown in
Figure 2, the MSB is represented first in the data output serial
stream. However, using Address 0x000, Bit 6, this order can be
inverted so that the LSB is represented first in the data output serial
stream.
SCLK Pin
The SCLK pin is required to operate the SPI. The pin has an
internal 30 kΩ pull-down resistor that pulls this pin low and is
only 1.8 V tolerant. To drive the SCLK pin from a 3.3 V logic
level, insert a 1 kΩ resistor in series with this pin to limit the
current.
Digital Output Test Patterns
Nine digital output test pattern options can be initiated through the
SPI using Address 0x0D. These options are useful when validating
receiver capture and timing. See Table 16 for the output test
mode bit sequencing options. Some test patterns have two serial
sequential words and can be alternated in various ways depending
on the test pattern chosen. Note that some patterns may not
adhere to the data format select option. In addition, custom
user defined test patterns can be assigned in the user pattern
registers (Address 0x019 through Address 0x020). All test mode
options except the pseudonoise (PN) sequence short and PN
sequence long can support 8- to 14-bit word lengths to verify
data capture to the receiver.
CSB Pin
The CSB pin is required to operate the SPI. The pin has an
internal 70 kΩ pull-up resistor that pulls this pin high and is
only 1.8 V tolerant. To drive the CSB pin from a 3.3 V logic
level, insert a 1 kΩ resistor in series with this pin to limit the
current.
RBIAS Pin
To set the internal core bias current of the ADC, place a resistor
nominally equal to 10.0 kΩ to ground at the RBIAS pin. Using a
resistor other than the recommended 10.0 kΩ resistor for RBIAS
degrades the performance of the device. Therefore, it is imperative
that at least a 1% tolerance on this resistor be used to achieve
consistent performance.
The PN sequence short pattern produces a pseudorandom bit
sequence that repeats itself every 29 − 1 bits, or 511 bits. A
description of the PN sequence short pattern and how it is
generated can be found in Section 5.1 of the ITU-T O.150 (05/96)
standard. However, the PN sequence long pattern differs from
the ITU-T O.150 (05/96) standard because it begins with a specific
value instead of 1s (see Table 15 for the initial values).
VREF Pin
A stable and accurate 0.5 V voltage reference is built into the
AD9674. This voltage reference is gained up internally by a factor
of 2, setting VREF to 1.0 V, which results in a full-scale differential
input span of 2.0 V p-p for the ADC. VREF is set internally by
default, but the VREF pin can be driven externally with a 1.0 V
reference to achieve more accuracy. However, the AD9674 does
not support ADC full-scale ranges less than 2.0 V p-p.
The PN sequence long pattern produces a pseudorandom bit
sequence that repeats itself every 223 − 1 bits, or 8,388,607 bits.
A description of the PN sequence long pattern and how it is
generated can be found in Section 5.6 of the ITU-T O.150 (05/96)
standard. The PN sequence long pattern differs from the standard,
however, because the starting value of the pattern is a specific
value rather than a value of only 1s and the AD9674 inverts the
bit stream (see Table 15 for the initial values). The output sample
size depends on the selected bit length.
When applying the decoupling capacitors to the VREF pin, use
ceramic, low equivalent series resistance (ESR) capacitors. Ensure
that these capacitors are close to the reference pin and on the same
layer of the PCB as the AD9674. The VREF pin must have both
a 0.1 µF capacitor and a 1 µF capacitor that are connected in
parallel to the analog ground. These capacitor values are recom-
mended for the ADC to properly settle and acquire the next valid
sample.
Rev. A | Page 30 of 47
Data Sheet
AD9674
Table 16. Flexible Output Test Modes
Output Test
Mode Bit
Sequence
Subject to
Resolution
Select
Pattern Name
Digital Output Word 1
Not applicable
Digital Output Word 2
Not applicable
Same
Same
Same
01 0101 0101 0101
Not applicable
Not applicable
00 0000 0000 0000
0000
0001
0010
0011
0100
0101
0110
0111
Off (default)
Midscale short
Not applicable
10 0000 0000 0000
11 1111 1111 1111
00 0000 0000 0000
10 1010 1010 1010
Not applicable
Yes
Yes
Yes
No
Yes
Yes
No
Positive full-scale short
Negative full-scale short
Checkerboard
PN sequence long
PN sequence short
Not applicable
One-word/zero-word toggle 11 1111 1111 1111
1000
1111
User input
Ramp output
Address 0x019 and Address 0x01A Address 0x01B and Address 0x01C No
00 0000 0000 0000 00 0000 0000 0001 Yes
General-Purpose Output Pins
The test signal amplitude at the input to the ADC can be calculated
given the LNA gain, attenuator control voltage, and the PGA gain.
The general-purpose output pins, GPO0, GPO1, GPO2 and GPO3,
can be used in a system to provide programmable inputs to
other chips in the system. The value of each pin is set via
Address 0x00E to either Logic 0 or Logic 1 (see Table 25).
Table 18 and Table 19 give example calculations.
Table 18. Test Signal Fundamental Amplitude at ADC Input,
VGAIN = 0 V, PGA Gain = 21 dB
Address 0x116,
Chip Address Pins
The chip address pins can be used to address individual AD9674
chips among multiple chips in a system. The chip address mode is
enabled using Address 0x115, Bit 5 (see Table 25). If the value
written to Bits[4:0] matches the value on the chip address bit pins
(ADDR4 to ADDR0]), the device is selected and any subsequent
SPI writes or reads to addresses indicated as chip registers are
written only to that device. If chip address mode is disabled, all
addresses can be written to regardless of the value on the address
pins.
Bits[3:2], Analog
Test Tones
LNA Gain
15.6 dB
LNA Gain
17.9 dB
LNA Gain
21.6 dB
00 (default)
01
10
−29 dBFS
−23 dBFS
−17 dBFS
−28 dBFS
−22 dBFS
−16 dBFS
−26 dBFS
−20 dBFS
−14 dBFS
Table 19. Test Signal Fundamental Amplitude at ADC Input,
GAIN = 0 V, PGA Gain = 30 dB
V
Address 0x116,
Bits [3:2], Analog
Test Tones
ANALOG TEST SIGNAL GENERATION
LNA Gain LNA Gain
LNA Gain
21.6 dB
15.6 dB
−20 dBFS
−14 dBFS
−8 dBFS
17.9 dB
−19 dBFS
−13 dBFS
−7 dBFS
The AD9674 can generate analog test signals that can be switched
to the input of the LNA of each channel to be used for channel
gain calibration. The test signal amplitude at the LNA output is
dependent on LNA gain, as shown in Table 17.
00 (default)
01
10
−17 dBFS
−11 dBFS
−5 dBFS
Table 17. Test Signal Fundamental Amplitude at LNA Output
Address 0x116,
Bits[3:2], Analog
Test Tones
LNA Gain
15.6 dB
LNA Gain
17.9 dB
LNA Gain
21.6 dB
00 (default)
80 mV p-p
98 mV p-p
119 mV p-p
01
10
160 mV p-p 196 mV p-p 238 mV p-p
320 mV p-p 391 mV p-p 476 mV p-p
Rev. A | Page 31 of 47
AD9674
Data Sheet
The RESET signal can be either a continuous signal or a single
pulse, and can be either synchronized with the MLO clock edge
(recommended) or it can be asynchronous. If a continuous signal is
used for the RESET , it must be at the LO rate. For a
synchronous RESET , the device can be configured to sample
the RESET signal with either the falling or rising edge of the
MLO clock, which makes it easier to align the RESET signal
with the opposite MLO clock edge. Register 0x02E is used to
configure the RESET signal behavior. Synchronize the RESET
input to the MLO input. Accurate channel to channel phase
matching can be achieved via a common clock on the RESET
input when using more than one AD9674 device.
CW DOPPLER OPERATION
Each channel of the AD9674 includes an I/Q demodulator. Each
demodulator has an individual programmable phase shifter.
The I/Q demodulator is ideal for phased array beamforming
applications in medical ultrasound. Each channel can be
programmed for 16 phase settings/360° (or 22.5°/step), selectable
via the SPI port. The device has a RESET input that is used to
synchronize the LO dividers of each channel. If multiple AD9674
devices are used, a common reset across the array ensures a synch-
ronized phase for all channels. Internal to the AD9674, the
individual Channel I and Channel Q outputs are current summed.
If multiple AD9674 devices are used, the I and Q outputs from
each AD9674 can be current summed and converted to a voltage
using an external transimpedance amplifier.
I/Q Demodulator and Phase Shifter
The I/Q demodulators consist of double balanced, harmonic
rejection, passive mixers. The RF input signals are converted
into currents by transconductance stages that have a maximum
differential input signal capability matching the full-scale LNA
output. These currents are then presented to the mixers, which
convert them to baseband (RF − LO) and 2× RF (RF + LO).
The signals are phase shifted according to the codes that are
programmed into the SPI latch (see Table 20). The phase shift
function is an integral part of the overall circuit. The phase shift
listed in Table 20 is defined as being between the baseband I or Q
channel outputs. As an example, for a common signal applied to
a pair of RF inputs to an AD9674, the baseband outputs are in
phase for matching phase codes. However, if the phase code for
Channel 1 is 0000 and the phase code for Channel 2 is 0001,
Channel 2 leads Channel 1 by 22.5°.
Quadrature Generation
The internal 0° and 90° LO phases are digitally generated by a
divide by M logic circuit, where M is 4, 8, or 16. The internal
divider is selected via Address 0x02E, Bits[2:1] (see Table 25). The
divider is dc-coupled and inherently broadband; the maximum
LO frequency is limited only by its switching speed. The duty
cycle of the quadrature LO signals must be as close to 50% as
possible for the 4LO and 8LO modes. The 16LO mode does not
require a 50% duty cycle. Furthermore, the divider is implemented
so the multiple LO signal reclocks the final flip flops that generate
the internal LO signals and, therefore, minimizes noise introduced
by the divide circuitry.
For optimum performance, the MLO input is driven differentially,
as on the AD9670 evaluation board. The common-mode voltage
on each pin is approximately 1.2 V with the nominal 3 V supply.
It is important to ensure that the MLO source has very low phase
noise (jitter), a fast slew rate, and an adequate input level to
obtain optimum performance of the CW signal chain.
Table 20. Phase Select Code for Channel to Channel Phase Shift
Φ Shift I/Q Demodulator Phase (Address 0x02D, Bits[3:0])
0°
0000
22.5°
45°
0001 (not valid in 4LO mode)
0010
Beamforming applications require a precise channel-to-channel
phase relationship for coherence among multiple channels. The
RESET input is provided to synchronize the LO divider circuits in
different AD9674 devices when they are used in arrays. The
RESET input is a synchronous edge triggered input that resets the
dividers to a known state after power is applied to multiple
AD9674 devices.
67.5°
90°
0011 (not valid in 4LO mode)
0100
0101 (not valid in 4LO mode)
0110
0111 (not valid in 4LO mode)
1000
1001 (not valid in 4LO mode)
1010
1011 (not valid in 4LO mode)
1100
112.5°
135°
157.5°
180°
202.5°
225°
247.5°
270°
292.5°
315°
337.5°
1101 (not valid in 4LO mode)
1110
1111 (not valid in 4LO mode)
Rev. A | Page 32 of 47
Data Sheet
AD9674
DIGITAL RF DECIMATOR
The AD9674 contains digital processing capability. Each channel
has two stages of processing available: RF decimator and HPF.
For test purposes, the input to the decimator can be a test
waveform. Normally, the input to the decimator is the output of
the ADC. The output of the decimator and filter is sent to the
serializer for output formatting.
When writing or reading in stream mode while the SPI
configuration is set to MSB first mode (default setting for
Register 0x000), the write/read address must refer to the last
register address, not the first one. For example, when writing or
reading the first profile that spans the address space between
0xF00 and 0xF07, and the SPI port is configured as MSB first,
the referenced address must be 0xF07 to allow reading from or
writing to the 64-bit profile in MSB mode. For more information
about stream mode, see the AN-877 Application Note, Interfacing
to High Speed ADCs via SPI.
The maximum data rate of the serializer is 1000 MSPS. Therefore,
if the sample rate of the ADC is greater than 65 MSPS, the RF
decimator (fixed rate of 2) must be enabled. The ADC resolution
is 14 bits. Saturation of the ADC is determined after the dc offset
calibration to ensure maximum dynamic range.
A buffer in the device stores the current profile data. When the
profile index is written in Register 0x10C, the selected profile is
read from memory and stored in the current profile buffer. The
profile memory is read/written in the SPI clock domain. After
the SPI writes the profile index value, it takes four SPI clock cycles
to read the profile from RAM and store it in the current profile
buffer. If the SPI is in LSB mode, these additional SPI clock cycles
are provided when the profile index register is written. If the SPI is
in MSB mode, an additional byte needs to be read or written to
update the profile buffer.
VECTOR PROFILE
To minimize the time needed to reconfigure device settings
while operating, the device supports configuration profiles. Up
to 32 profiles can be stored in the device. A profile is selected by a
5-bit index. A profile consists of a 64-bit vector, as described in
Table 21. Each parameter is concatenated to form the 64-bit profile
vector. The profile memory starts at Address 0xF00 and ends at
Address 0xFFF. The memory can be written in either stream
mode or address selected data mode. However, the memory
must be read using stream mode.
Updating the profile memory does not affect the data in the profile
buffer. The profile index register must be written to cause a refresh
of the current profile data, even if the profile index register is
written with the same value.
RF DECIMATOR
MULTIBAND AAF
DECIMATE BY 2
ADC OUTPUT OR
TEST WAVEFORM
HIGH-PASS
FILTER
FRAMER
SERIALIZER
DC OFFSET
CALIBRATION
Figure 49. Simplified Block Diagram of a Single Channel of RF Decimator
Table 21. Profile Definition
Field
Bits
Description
Reserved
HPF bypass
32
1
Reserved
Digital HPF bypass
0 = disable (filter enabled)
1 = enable (filter bypassed)
POWER_START
15
ADC clock cycles counted from TX_TRIG when the active channels are powered up
0x0000 = 0 clock cycles
0x0001 = 1 clock cycle
…
0x7FFF = 32,767 clock cycles
Reserved
1
Reserved
POWER_STOP
15
ADC clock cycles counted from TX_TRIG when the active channels are powered down
0x0000 = 0 clock cycles
0x0001 = 1 clock cycle
…
0x7FFF = Continuous run mode
Rev. A | Page 33 of 47
AD9674
Data Sheet
High-Pass Filter
RF DECIMATOR
A second-order Butterworth, high-pass, infinite impulse response
(IIR) filter can be applied after the RF decimator. The IIR filter
has a settling time of 2.5 µs and a cutoff frequency of 700 kHz
for an encode clock of 50 MHz. Therefore, if the ADC clock is
50 MHz, the first 125 samples (2.5 µs/0.02 µs) must be ignored.
The filter can be bypassed or enabled in the vector profile if the
filter is enabled using Address 0x113, Bit 5. If the filter is
bypassed by setting Address 0x113, Bit 5, to 1, the filter cannot
be enabled from the vector profile.
The input to the RF decimator is either the ADC output data or
a test waveform, as described in the Digital Test Waveforms section.
The test waveforms are enabled per channel using Address 0x11A
(see Table 25).
DC Offset Calibration
DC offset can be reduced through a manual system calibration
process. The dc offset of every channel in the system is measured,
followed by setting a calibration value in Address 0x110 and
Address 0x111. Note that these registers are both chip and local
addresses, meaning the registers are accessed using the chip address
and device index. The dc offset calibration can be bypassed
using Address 0x10F, Bits[2:0].
DIGITAL TEST WAVEFORMS
Digital test waveforms can be used in the digital processing block
instead of the ADC output. To enable digital test waveforms,
use Address 0x11B. Each channel can be individually enabled in
Address 0x11A.
Multiband AAF and Decimate by 2
The multiband filter is a finite impulse response (FIR) filter. It is
programmable with low or high band filtering. The filter requires
11 input samples to populate the filter. The decimation rate is fixed
at 2×. Therefore, the decimation frequency is fDEC = fSAMPLE/2.
Figure 50 and Figure 51 show the frequency response of the filter,
depending on this mode. Figure 50 shows the attenuation amp-
litude over the Nyquist frequency range. Figure 51 shows the
pass band response as nearly flat.
Waveform Generator
For testing and debugging, a programmable waveform generator
can be used in place of ADC data. The waveform generator can
vary offset, amplitude, and frequency. The generator uses the ADC
sample frequency, fSAMPLE, and ADC full-scale amplitude, AFULL-SCALE
as references. The values are set in Address 0x117, Address 0x118,
and Address 0x119 (see Table 25).
,
10
x = C + A × sin(2 × π × N)
(8)
0
f
SAMPLE ×n
N =
, see Address 0x117
(9)
LOW BAND FILTER
HIGH BAND FILTER
64
–10
–20
–30
–40
–50
–60
AFULL−SCALE
A =
, see Address 0x118
(10)
(11)
2x
C = AFULL-SCALE × a × 2−(13 − b), see Address 0x119
Channel ID and Ramp Generator
In Channel ID test mode, the output is a concatenated value.
Bits[6:0] are a ramp. Bit 7 is reserved as 0. Bits[10:8] are the
channel ID such that Channel A is coded as 000 and Channel B
is 001. Bits[15:11] compose the chip address.
0
2
4
6
8
10
12
14
16
18
20
FREQUENCY (MHz)
Figure 50. AAF Frequency Response
(Frequency Scale Assumes fADC = 2 × fDEC = 40 MHz)
2
1
0
–1
–2
–3
–4
–5
–6
–7
–8
LOW BAND FILTER
HIGH BAND FILTER
0
2
4
6
8
10
12
14
16
18
20
FREQUENCY (MHz)
Figure 51. AAF Frequency Response Zoomed In
(Frequency Scale Assumes fADC = 2 × fDEC = 40 MHz)
Rev. A | Page 34 of 47
Data Sheet
AD9674
CHIP IN POWER-DOWN,
STANDBY,
DIGITAL BLOCK POWER SAVING SCHEME
OR CW MODE
To reduce power consumption in the digital block after the ADC,
the RF decimator and filter start in an idle state after running
the chip (Register 0x008, Bits[2:0] = 000). The digital block only
switches to a running state when the negative edge of the TX_TRIG
signal pulse is detected, or with a software TX_TRIG signal write
(Register 0x10C, Bit 5 = 1).
RUN CHIP
DIGITAL
DECIMATOR/FILTER
IDLE
TX_TRIG IS HIGH, PROFILE
INDEX WRITE, OR POWER
STOP EXPIRES
NEGATIVE EDGE TX_TRIG
OR SOFTWARE TX_TRIG
To put the digital block back into the idle state (while the rest of
the chip is still running) and save power, raise the TX_TRIG
signal high or write to the profile index (Register 0x10C, Bits[0:4]).
The digital block will also switch to the idle state if the power
stop expires when using the advanced power control feature.
Figure 52 illustrates the digital block power saving scheme.
DIGITAL
DECIMATOR/FILTER
RUNNING
Figure 52. Digital Block Power Saving Scheme
Rev. A | Page 35 of 47
Data Sheet
AD9674
SERIAL PORT INTERFACE (SPI)
Although the device is synchronized during power-up, caution
must be exercised when using 2-wire mode to ensure that the serial
port remains synchronized with the CSB line. When operating
in 2-wire mode, it is recommended that a 1-, 2-, or 3-byte transfer
be used exclusively. Without an active CSB line, streaming
mode can be entered but not exited.
The AD9674 SPI allows the user to configure the signal chain for
specific functions or operations through the structured register
space provided inside the chip. The SPI offers the user added
flexibility and customization, depending on the application.
Addresses are accessed via the serial port and can be written to
or read from via the port. Memory is organized into bytes that
can be further divided into fields, as documented in the Memory
Map section. For detailed operational information, see the AN-877
Application Note, Interfacing to High Speed ADCs via SPI.
In addition to word length, the instruction phase determines
whether the serial frame is a read or write operation, allowing
the serial port to be used both to program the chip and to read
the contents of the on-chip memory. If the instruction is a read-
back operation, performing a readback causes the SDIO pin to
change direction from an input to an output at the appropriate
point in the serial frame.
The SCLK, SDIO, and CSB pins define the SPI (see Table 22). The
SCLK (serial clock) pin synchronizes the read and write data
presented to the device. The SDIO pin is a dual-purpose pin that
allows data to be sent to and read from the internal memory map
registers of the device. The CSB pin is an active low control that
enables or disables the read and write cycles.
Data can be sent in MSB first mode or LSB first mode. MSB
first mode is the default at power-up and can be changed by
adjusting the configuration register (Address 0x00). For more
information about this and other features, see the AN-877
Application Note, Interfacing to High Speed ADCs via SPI.
Table 22. Serial Port Pins
Pin
Function
SCLK
Serial clock. Serial shift clock input. SCLK is used to
synchronize serial interface reads and writes.
HARDWARE INTERFACE
SDIO
Serial data input/output. Dual-purpose pin that
typically serves as an input or an output, depending
on the instruction sent and the relative position in
the timing frame.
Chip select bar (active low). This control gates the
read and write cycles.
The pins described in Table 22 constitute the physical interface
between the programming device and the serial port of the
AD9674. The SCLK and CSB pins function as inputs when
using the SPI. The SDIO pin is bidirectional, functioning as an
input during write phases and as an output during readback.
CSB
If multiple SDIO pins share a common connection, ensure that
proper VOH levels are met. Figure 53 shows the number of SDIO
pins that can be connected together and the resulting VOH levels,
assuming the same load for each AD9674.
The falling edge of CSB, in conjunction with the rising edge of
SCLK, determines the start of the framing sequence. During the
instruction phase, a 16-bit instruction is transmitted, followed
by one or more data bytes, which is determined by the W0 and
W1 bit fields. An example of the serial timing and definitions are
shown in Figure 54 and Table 23.
1.800
1.795
1.790
1.785
1.780
1.775
1.770
1.765
1.760
1.755
1.750
1.745
1.740
1.735
1.730
1.725
1.720
1.715
During normal operation, CSB signals to the AD9674 that SPI
commands must be received and processed. When CSB is
brought low, the device processes SCLK and SDIO to execute
instructions. Normally, CSB remains low until the communication
cycle is complete. However, if connected to a slow device, CSB
can be brought high between bytes, allowing older microcontrollers
enough time to transfer data into shift registers. CSB can be
stalled when transferring one, two, or three bytes of data. When
W0 and W1 are set to 11, the device enters streaming mode and
continues to process data, either reading or writing, until CSB is
taken high to end the communication cycle. This mode allows
complete memory transfers without the need for additional
instructions. Regardless of the mode, if CSB is taken high in the
middle of a byte transfer, the SPI state machine is reset, and the
device waits for a new instruction.
0
10
20
30
40
50
60
70
80
90
100
NUMBER OF SDIO PINS CONNECTED TOGETHER
Figure 53. SDIO Pin Loading
This interface is flexible enough to be controlled either by
serial programmable read-only memories (PROMs) or by PIC
microcontrollers, which provide the user with an alternative to a
full SPI controller for programming the device (see the AN-812
Application Note, Microcontroller-Based Serial Port Interface (SPI®)
Boot Circuit).
The SPI port can be configured to operate in different manners.
CSB can also be tied low to enable 2-wire mode. When CSB is
tied low, SCLK and SDIO are the only pins required for
communication.
Rev. A | Page 36 of 47
Data Sheet
AD9674
tDS
tHIGH
tCLK
tH
tS
tDH
tLOW
CSB
DON’T
SCLK
DON’T
CARE
CARE
DON’T
CARE
DON’T
CARE
R/W
W1
W0
A12
A11
A10
A9
A8
A7
SDIO
D5
D4
D3
D2
D1
D0
Figure 54. Serial Timing Details
Table 23. Serial Timing Definitions
Parameter Timing (ns min) Description
tDS
tDH
tCLK
tS
12.5
5
40
5
Setup time between the data and the rising edge of SCLK
Hold time between the data and the rising edge of SCLK
Period of the clock
Setup time between CSB and SCLK
tH
2
Hold time between CSB and SCLK
tHIGH
tLOW
tEN_SDIO
16
16
15
Minimum period that SCLK must be in a logic high state
Minimum period that SCLK must be in a logic low state
Minimum time for the SDIO pin to switch from an input to an output relative to the SCLK falling edge
(not shown in Figure 54)
tDIS_SDIO
15
Minimum time for the SDIO pin to switch from an output to an input relative to the SCLK rising edge (not
shown in Figure 54)
Rev. A | Page 37 of 47
AD9674
Data Sheet
MEMORY MAP
READING THE MEMORY MAP TABLE
RESERVED LOCATIONS
Each row in the memory map register table has eight bit locations.
The memory map is roughly divided into two sections: the chip
configuration register map (Address 0x000 to Address 0x1A1)
and the profile register map (Address 0xF00 to Address 0xFFF).
Registers that are designated as local registers use the device
index in Address 0x004 and Address 0x005 to determine to
which channels of a device the command is applied. Registers
that are designated as chip registers use the chip address mode
in Address 0x115 to determine whether the device is to be
updated by writing to the chip register.
Do not write to undefined memory locations except when writing
the default values suggested in this data sheet. Addresses that have
values marked as 0 must be considered reserved and have a
0 written into their registers during power-up.
DEFAULT VALUES
After a reset, critical registers are automatically loaded with default
values. These values are indicated in Table 25, where an X refers
to an undefined feature.
LOGIC LEVELS
The address hex column of Table 25 indicates the register address.
The default value is shown in the default value column. The Bit 7
(MSB) column is the start of the default hexadecimal value given.
For example, Address 0x009, the global clock register, has a default
value of 0x01, meaning that Bit 7 = 0, Bit 6 = 0, Bit 5 = 0, Bit 4 = 0,
Bit 3 = 0, Bit 2 = 0, Bit 1 = 0, and Bit 0 = 1, or 0000 0001 in binary.
This setting is the default for the duty cycle stabilizer in the on
condition.
“Bit is set” is synonymous with “bit is set to Logic 1” or “writing
Logic 1 for the bit.” Similarly, “bit is cleared” is synonymous
with “bit is set to Logic 0” or “writing Logic 0 for the bit.”
RECOMMENDED START-UP SEQUENCE
To save system power during programming, the AD9674 powers
up in power-down mode. To start the device up and initialize
the data interface, the SPI commands listed in Table 24 are
recommended. At a minimum, the profile memory for an index of
0 must be written (Address 0xF00 to Address 0xF03). If additional
profiles and coefficient memory are required, these can be written
after Profile Memory 0.
For more information about the SPI memory map and other
functions, see the AN-877 Application Note, Interfacing to
High Speed ADCs via SPI.
Rev. A | Page 38 of 47
Data Sheet
AD9674
Table 24. SPI Write Start-Up Sequence Example
Address
0x000
0x002
0x0FF
0x004
0x005
0x113
0x011
0xF00
0xF01
0xF02
0xF03
0x10C1
0x014
0x008
0x021
0x199
0x19B
0x188
0x18B
0x18C
0x182
0x10C3
0x00F
0x02B
Value
Description
0x3C
0x0X (default)
0x01
0x0F
0x3F
0x00
0x06 (default)
0xFF
0x7F
0x00
0x80
0x00 (default)
0x00
0x00
0x05
0x80
0x50
0x01
0x27
Initiates SPI reset
Sets speed mode to 40 MHz
Enables speed mode change (required after Register 0x002 writes)
Sets local registers to all channels
Sets local registers to all channels
Bypasses RF decimator; enable digital HPF
Sets LNA gain = 21.6 dB, VGA gain = external, and PGA gain = 24 dB
Continuous run mode enabled; do not power down channels (POWER_STOP LSB)
Continuous run mode enabled; do not power down channels (POWER_STOP MSB)
Powers up all channels 0 clock cycles after TX_TRIG (POWER_STOP LSB)
Digital high-pass bypassed (POWER_STOP MSB)
Sets the profile index (required after profile memory writes)
Sets output data format
TGC run mode2
14 bits, 8 lanes, frame clock output (FCO) covers entire frame
Enables automatic clocks per sample calculation
Serial format
Enables start code
Sets start code MSB
Sets start code LSB
Autoconfigures PLL
Sets SPI TX_TRIG and profile index
Sets low-pass filter cutoff frequency and bandwidth mode
Sets analog LPF and HPF to defaults, tune filters4
0x72
0x82
0x20
0x18 (default)
0x40
1 Setting the profile index requires an additional SPI write in SPI MSB mode before the chip runs to complete the current profile buffer update.
2 Running the chip from full power-down mode requires 375 µs wake-up time, as listed in Table 3.
3 Software TX_TRIG switches the demodulator/decimator digital block to a running state. The software TX_TRIG signal may not be needed if a hardware TX_TRIG signal
is used to run the digital block.
4 Tuning the filters requires 512 ADC clock cycles.
Rev. A | Page 39 of 47
Data Sheet
AD9674
Table 25. Memory Map Registers
Addr.
Default
Value Comments
(Hex) Register Name
Bit 7 (MSB)
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0 (LSB)
Chip Configuration Registers
0x000 CHIP_PORT_
CONFIG
0
LSB first:
0 = off
(default),
1 = on
SPI reset:
0 = off
(default),
1 = on
1
1
SPI reset: LSB first:
0 = off 0 = off
(default), (default),
0
0x18
Mirror nibbles so LSB first
or MSB Mode I is set
correctly regardless of
shift mode. SPI reset
reverts all registers
(including LVDS registers),
except Register 0x000, to
their default values, and
Register 0x000, Bit 2 and
Bit 5 bits automatically
clear.
1 = on
1 = on
f0x001 CHIP_ID
Chip ID, Bits[7:0] (AD9674 = 0xA8), default
0xA8 Default is unique chip ID,
different for each device;
read only register.
0x002 CHIP_GRADE
X
X
X
X
Speed mode, Bits[5:4]
(identify device
variants of chip ID):
X
X
X
X
X
X
0x0X Speed mode used to
differentiate ADC speed
power modes (must
00 = Mode I
update Register 0x0FF after
for the speed mode
changes to take effect).
(40 MSPS) (default),
01 = Mode II (65 MSPS),
10 = Mode III (80 MSPS),
11 = Mode III (125 MSPS)
0x0FF DEVICE_UPDATE
X
X
X
X
0x00
A write to Register 0x0FF
(value does not matter)
resets all default register
values (analog and ADC
registers only; not
JESD204B ones and not
Register 0x00 or
Register 0x02, Bits[5:4]) if
Register 0x02 has been
previously written since
the last reset/load of
defaults.
0x004 DEVICE_INDEX_2
0x005 DEVICE_INDEX_1
X
X
X
X
X
X
Data
Data
Data
Data
0x0F Bits are set to determine
which on-chip channel
receives the next write
command.
Channel H: Channel G: Channel F: Channel E:
0 = off,
1 = on
0 = off,
1 = on
0 = off,
1 = on
0 = off,
1 = on
(default)
(default) (default) (default)
Clock
Channel
DCO
0 = off,
1 = on
Clock
Channel
FCO
0 = off,
1 = on
Data
Data Data Data
0x3F Bits are set to determine
which on-chip channel
receives the next write
command.
Channel D: Channel C: Channel B: Channel A:
0 = off,
1 = on
:
:
0 = off,
1 = on
0 = off,
1 = on
0 = off,
1 = on
(default)
(default) (default) (default)
(default) (default)
0x008 GLOBAL_MODES
X
X
LNA input
impedance:
0 = 6 kΩ
(default),
1 = 3 kΩ
X
0
0
Internal power-down mode:
000 = chip run (TGC mode),
001 = full power-down (default),
010 = standby,
011 = reset all LVDS registers,
100 = CW Doppler mode
(TGC is powered down)
0x01 Determines generic
modes of chip operation
(global).
0x009 GLOBAL_CLOCK
0x00A PLL_STATUS
X
X
X
X
X
X
X
X
X
X
X
DCS:
0x01 Turns the internal DCS on
and off (global).
0 = off,
1 = on
(default)
PLL lock status:
0 = not locked
(default),
X
X
0x00 Monitor PLL lock status
(read only, global).
1 = locked
Rev. A | Page 40 of 47
Data Sheet
AD9674
Addr.
(Hex) Register Name
Default
Value Comments
Bit 7 (MSB)
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0 (LSB)
0x00D TEST_IO
User test mode: 0 =
continuous, repeat
user patterns
X
Reset PN Reset PN
long gen short gen:
Output test mode:
0000 = off (default),
0001 = midscale short,
0x00 When register is set, the
test data is placed on the
output pins in place of
0 = on,
0 = on,
(1, 2, 3, 4, 1, 2, 3, 4, …)
(default), 1 = single
clock cycle user
patterns, then zeros
(1, 2, 3, 4, 0, 0, …)
PN long
running
(default), (default),
1 = off,
PN long
held in
reset
PN short
running
0010 = positive full-scale short,
0011 = negative full-scale short,
0100 = checkerboard output,
0101 = PN sequence long,
0110 = PN sequence short,
0111 = one-word/zero-word toggle,
1000 = user input,
normal data (local).
1 = off,
PN short
held in
reset
1001:1110 = reserved,
1111 = ramp output (see Table 16)
0x00E GPO
X
X
X
X
GPO3
GPO2
output:
0 = low
GPO1
output: output:
0 = low 0 = low
GPO0
0x00 Values placed on GPOx
pins (global).
output:
0 = low
(default);
1 = high
(default); (default): (default);
1 = high 1 = high 1 = high
0x00F FLEX_CHANNEL
_INPUT
Filter cutoff frequency control:
Band
mode:
0 = low
(default,
8 MHz to
18 MHz),
1 = high
(13.5 MHz
to 30 MHz)
X
X
0x18
Antialiasing filter cutoff
(global).
00000 = 1.45 × (1/3) × fSAMPLE
00001 = 1.25 × (1/3) × fSAMPLE
00010 = 1.13 × (1/3) × fSAMPLE
,
,
,
00011 = 1.0 × (1/3) × fSAMPLE (default),
00100 = 0.9 × (1/3) × fSAMPLE
00101 = 0.8 × (1/3) × fSAMPLE
00110 = 0.75 × (1/3) × fSAMPLE
00111 = reserved,
,
,
,
01000 = 1.45 × (1/4.5) × fSAMPLE
01001 = 1.25 × (1/4.5) × fSAMPLE
01010 = 1.13 × (1/4.5) × fSAMPLE
,
,
,
01011 = 1.0 × (1/4.5) × fSAMPLE
01100 = 0.9 × (1/4.5) × fSAMPLE
01101 = 0.8 × (1/4.5) × fSAMPLE
01110 = 0.75 × (1/4.5) × fSAMPLE
01111 = reserved,
,
,
,
,
10000 = 1.45 × (1/6) × fSAMPLE
10001 = 1.25 × (1/6) × fSAMPLE
10010 = 1.13 × (1/6) × fSAMPLE
,
,
,
10011 = 1.0 × (1/6) × fSAMPLE
10100 = 0.9 × (1/6) × fSAMPLE
10101 = 0.8 × (1/6) × fSAMPLE
,
,
,
10110 = 0.75 × (1/6) × fSAMPLE
,
1 0111 = reserved
0x010 FLEX_OFFSET
0x011 FLEX_GAIN
X
X
1
0
0
0
0
0
0x20
0x06
Reserved.
Digital VGA gain control:
0000 = GAIN pins enabled (default),
0001 = 0.0 dB (maximum gain, GAIN pins disabled),
PGA gain:
LNA gain:
00 = 15.6 dB,
01 = 17.9 dB,
10 = 21.6 dB
(default)
LNA and PGA gain
adjustment (global).
00 = 21 dB,
01 = 24 dB (default),
10 = 27 dB,
0010 = −3.5 dB,
0011 = −7.0 dB,
….,
11 = 30 dB
1110 = 45 dB
1111 = 45 dB
0x012 BIAS_CURRENT
X
X
X
X
0
1
0
PGA bias:
0 = 100%
(default),
1 = 60%
LNA bias:
00 = high,
01 = midhigh (default),
10 = midlow,
0x09
0x00
LNA bias current
adjustment (global).
11 = low
0x013 RESERVED_13
0
0
0
0
0
0
Reserved.
0x014 OUTPUT_MODE
X
X
X
Output data X
enable:
0 = enable
(default),
Output
data
invert:
0=disable
(default),
1 =enable
Output data format: 0x01
00 = offset binary,
01 = twos complement
(default),
Data output modes (local).
1 = disable
10 = gray code,
11 = reserved
0x015 OUTPUT_ADJUST LVDS output
1
1
0
LVDS drive
strength
enable:
0=disable
(default),
1 = enable
LVDS drive current:
000 = 3.72 mA,
001 = 3.5 mA (default),
010 = 3.30 mA,
0x61
Data output levels (global).
standard:
0 = ANSI-644
(default),
1 = IEEE 1596.3
(low power)
011 = 2.96 mA,
100 = 2.82 mA,
101 = 2.57 mA,
110 = 2.27 mA,
111 = 2.0 mA (reduced range)
Rev. A | Page 41 of 47
AD9674
Data Sheet
Addr.
(Hex) Register Name
Default
Value Comments
Bit 7 (MSB)
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0 (LSB)
0x016 FLEX_OUTPUT_
PHASE
X
X
0
DCO signal
invert:
0 = disable
(default),
1 = enable
X
X
DCO signal phase adjust 0x00
with respect to DOUT:
00 = +90° (default),
01 = 0°,
DCO signal inversion and
coarse phase adjustment
(global).
10 = 0°,
11 = −90°
0x017 FLEX_OUTPUT_
DELAY
DCO signal delay
enable:
0 = disable (default),
X
X
DCO signal clock delay:
00000: 100 ps (default),
00001 = 200 ps,
00010 = 300 ps,
…,
0x00
DCO signal delay (global).
1 = enable
11101 = 3.0 ns,
11110 = 3.1 ns,
11111 = 3.2 ns
0x018 RESERVED_018
X
X
X
X
X
1
0
0
0x04
0x00
Reserved (global).
0x019 USER_
PATT1_LSB
B7
B6
B5
B4
B3
B2
B1
B0
User-Defined Pattern 1,
LSB (global).
0x01A USER_
PATT1_MSB
B15
B7
B14
B6
B13
B5
B12
B4
B11
B3
B10
B2
B9
B1
B9
B1
B9
B1
B9
B8
B0
B8
B0
B8
B0
B8
0x00
0x00
0x00
0x00
0x00
0x00
0x00
User-Defined Pattern 1,
MSB (global).
0x01B USER_
PATT2_LSB
User-Defined Pattern 2,
LSB (global).
0x01C USER_
PATT2_MSB
B15
B7
B14
B6
B13
B5
B12
B4
B11
B3
B10
B2
User-Defined Pattern 2,
MSB (global).
0x01D USER_
PATT3_LSB
User-Defined Pattern 3,
LSB (global).
0x01E USER_
PATT3_MSB
B15
B7
B14
B6
B13
B5
B12
B4
B11
B3
B10
B2
User-Defined Pattern 3,
MSB (global).
0x01F USER_
PATT4_LSB
User-Defined Pattern 4,
LSB (global).
0x020 USER_
PATT4_MSB
B15
0
B14
B13
B12
B11
Lane low
B10
X
User-Defined Pattern 4,
MSB (global).
0x021 FLEX_
SERIAL_CTRL
FCO signal
invert:
0 = not
Lane mode:
Output word length: 0x00
00 = 12 bits (default),
01 = 14 bits,
LVDS control (global).
00 = 1-channel/lane rate:
(8 lanes) (default),
0 = normal
inverted
(default),
1 = inverted
01 = 2-channel/lane (default),
10 = 16 bits,
11 = reserved
(4 lanes),
10 = 4-channel/lane sample
(2 lanes), frequency
1 = low
11 = 8-channel/lane (<32 MHz)
(1 lane)
0x022 SERIAL_
CH_STAT
X
X
X
X
X
X
X
X
X
X
Channel
power-down:
1 = on,
0 = off
(default)
0x00
Used to power down
individual channels (local).
0x02B FLEX_FILTER
0x02C LNA_TERM
Enables
X
Bypass
analog HPF:
0 = off
(default),
1 = on
Analog high-pass filter 0x00
cutoff:
Filter cutoff (global);
(fLP = low-pass filter cutoff
frequency in MSPS).
automatic
low-pass
tuning:
1 = on
(self clearing)
00 = fLP/12 (default),
01 = fLP/9,
10 = fLP/6,
11 = fLP/3
X
X
X
X
X
X
LO-x, LOSW-x
connection:
0x00
LNA active termination/
input impedance (global).
00 = RFB1 (default),
01 = (RFB1||RFB2),
10 = RFB2
,
11 = ∞
Rev. A | Page 42 of 47
Data Sheet
AD9674
Addr.
(Hex) Register Name
Default
Value Comments
Bit 7 (MSB)
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0 (LSB)
0x02D CW_ENABLE_
PHASE
X
X
X
CW Doppler
channel
enable:
I/Q demodulator phase:
0000 = 0° (default),
0001 = 22.5° (not valid for 4LO mode),
0010 = 45°,
0x00
Phase of demodulators
(local, chip).
0 = off
(default),
1 = on
0011 = 67.5° (not valid for 4LO mode),
0100 = 90°,
0101 = 112.5° (not valid for 4LO mode),
0110 = 135°,
0111 = 157.5° (not valid for 4LO mode),
1000 = 180°,
1001 = 202.5° (not valid for 4LO mode),
1010 = 225°,
1011 = 247.5° (not valid for 4LO mode),
1100 = 270°,
1101 = 292.5° (not valid for 4LO mode),
1110 = 315°,
1111 = 337.5° (not valid for 4LO mode)
0x02E CW_LO_MODE
Partially enable
LVDS during CW
0: LVDS link
disabled during CW 0 = synchro- sampling 0 = active
(default), nous MLO high
1: LVDS link partially (default), clock edge: (default),
enabled during CW, 1 = asynchro- 0 = falling 1 = active
PLL, FCO, and DCO
are enabled, while
LVDS data drivers
are disabled
(switching activity
can degrade CW
performance)
RESET with Synchro-
MLO clock nous
RESET
signal
polarity:
MLO and
RESET
buffer enable
(in all modes
except
CW mode):
0 = power
down
(default),
1 = enable
LO mode
00X = 4LO, third to fifth odd
0x00
CW mode functions
(global).
edge:
RESET
harmonic rejection
(default)
010 = 8LO, third to fifth odd
harmonic rejection
011 = 8LO, third to 13th odd
harmonic rejection
nous
(default),
low
1 = rising
100 = 16LO, third to fifth odd
harmonic rejection
101 = 16LO, third to 13th odd
harmonic rejection
11X = reserved
0x02F CW_OUTPUT
CW output dc bias
voltage:
0
0
0
0
0
0
0
0x80
CW dc voltage output
control (global).
0 = bypass,
1 = enable (default)
0x102 RESERVED_102
0x103 RESERVED_103
0x104 RESERVED_104
0x105 RESERVED_105
0x106 RESERVED_106
0x107 RESERVED_107
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
1
0
0
0
0
0
1
0
0
X
0
0
1
0
9
X
0x00
0x00
0x3F
0x00
0x00
Reserved.
Reserved.
Reserved.
Reserved.
Reserved.
Read Reserved.
only
0x108 RESERVED_108
0x109 VGA_TEST
0
0
0
0
0
0
0
0
0x00
0x00
Reserved.
X
X
X
VGA/AAF
test mode
enable:
X
VGA/AAF output test mode:
000 = Channel A (default),
001 = Channel B,
VGA/AAF test mode,
enables AAF output to
GPO2 and GPO3 pins
(global).
0 = off
010 = Channel C,
(default),
1 = on
011 = Channel D,
100 = Channel E,
101 = Channel F,
110 = Channel G,
111 = Channel H
0x10C PROFILE_INDEX
X
X
Manual
TX_TRIG:
0 = off,
Profile index, Bits[4:0]
0x00
Index for profile memory;
selects active profile
(global).
use pin
(default),
1 = on,
auto
generate
TX_TRIG
(self clears)
0x10D RESERVED_10D
0x10E RESERVED_10E
0x10F DIG_OFFSET_CAL
1
1
0
1
1
0
1
1
0
1
1
0
1
1
1
1
1
1
1
1
0xFF
0xFF
0x00
Reserved.
Reserved.
Digital offset
calibration
status:
0 = not
complete
(default),
Digital offset calibration:
000 = disable correction, reset
correction value (default),
001 = average 210 samples,
010 = average 211 samples,
…,
Controls digital offset
calibration enable and
number of samples used
(global).
1 = complete
111 = average 216 samples
Rev. A | Page 43 of 47
AD9674
Data Sheet
Addr.
(Hex) Register Name
Default
Value Comments
Bit 7 (MSB)
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0 (LSB)
0x110 DIG_OFFSET_
CORR1
D7
D6
D5
D4
D3
D2
D1
D0
0x00
Offset correction LSB
(local, chip).
0x111 DIG_OFFSET_
CORR2
D15
D14
D13
D12
D11
D10
D9
D8
0x00
Offset correction MSB
(local, chip).
Digital offset calibration (read back if auto calibration enabled with Register 0x10F.
Otherwise, force correction value.)
Offset correction = [D15:D0] × AFULL-SCALE/216,
0111 1111 1111 1111 (215 − 1) = +1/2 × AFULL-SCALE − 1/216 × AFULL-SCALE
,
,
0111 1111 1111 1110 (215 − 2) = +1/2 × AFULL-SCALE − 2/216 × AFULL-SCALE
…,
0000 0000 0000 0001 (+1) = 1/216 × AFULL-SCALE
0000 0000 0000 0000 = no correction (default),
,
1111 1111 1111 1111 (−1) = −1/216 × AFULL-SCALE
,
…,
1000 0000 0000 0000 (−215) = −1/2 AFULL-SCALE
0x112 POWER_
MASK_CONFIG
X
X
X
X
X
Power-up setup time (POWER_SETUP):
0x02
0x00
Power setup time used to
set the power-up time
(global).
0 0000 = 0,
0 0001 = 1 × 40/fSAMPLE
,
0 0010 = 2 × 40/fSAMPLE (default),
0 0011 = 3 × 40/fSAMPLE
…,
,
1 1111 = 31 × 40/fSAMPLE
0x113 DIG_CONFIG
Digital
high-pass
filter:
0 = enable
(default),
1 = bypass
0
Decimator and
filter enable:
X
X
Enables stages of the
digital processing (global).
00 = RF 2× decimator
bypassed (default),
01 = RF 2× decimator
enabled and low
band filter,
1X = RF 2× decimator
enabled and high band
filter,
0x115 CHIP_ADDR_EN
X
X
X
X
Chip
address
mode:
0 =disable
(default),
1 = enable
Chip address qualifier:
0 0000 (default), if read, returns state of
Pin ADDR4 to Pin ADDR0
0x00
0x00
Chip address mode
enables the addressing of
specific devices if the value
of Bits[4:0] qualifier equals
the state on the ADDR4 to
ADDR0 pins (global).
0x116 ANALOG_
TEST_TONE
X
X
Analog test signal
amplitude
Analog test signal
frequency:
00 = fSAMPLE/4 (default),
01 = fSAMPLE/8,
Analog test tone
amplitude and frequency
(global).
(see Table 17 to
Table 19)
10 = fSAMPLE/16,
11 = fSAMPLE/32
0x117 DIG_SINE_
TEST_FREQ
X
X
X
X
X
X
Digital test tone frequency:
0 0000 = 1 × fSAMPLE/64,
0 0001 = 2 × fSAMPLE/64,
…,
0x00
0x00
Digital sine test tone
frequency (global).
1 1111 = 32 × fSAMPLE/64
0x118 DIG_SINE_
TEST_AMP
X
Digital test tone amplitude:
0000 = AFULL-SCALE (default),
0001 = AFULL-SCALE/2,
0010 = AFULL-SCALE/22,
…,
Digital sine test tone
amplitude (global).
1111 = AFULL-SCALE/215
0x119 DIG_SINE_
TEST_OFFSET
Offset multiplier (a):
0 1111 = 15,
0 1110 = 14,
…,
Offset exponent (b):
000 = 0 (default),
001 = 1,
0x00
Digital sine test tone offset
(global).
…,
0 0000 = 0 (default),
1 1111 = −1,
…,
111 = 7
1 0000 = −16
Offset = AFULL-SCALE × a × 2− (13 − b), offset range is ~0.5 dB,
maximum positive offset = 15 × 2− (13 − 7) = 0.25 × AFULL-SCALE
maximum negative offset = –16 × 2− (13 − 7) ≈ −0.25 × AFULL-SCALE
,
0x11A TEST_MODE_
CH_ENABLE
Channel H enable:
0 = off (default),
1 = on
Channel G
enable:
0 = off
Channel F Channel E Channel D
Channel C Channel B Channel A
0x00
Enables channels for test
mode (global).
enable:
0 = off
enable:
0 = off
enable:
0 = off
enable:
0 = off
enable:
0 = off
enable:
0 = off
(default),
(default),
(default),
(default),
(default), (default), (default),
1 = on
1 = on
1 = on
1 = on
1 = on 1 = on 1 = on
Rev. A | Page 44 of 47
Data Sheet
AD9674
Addr.
(Hex) Register Name
Default
Value Comments
Bit 7 (MSB)
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0 (LSB)
0x11B TEST_MODE_
CONFIG
X
X
X
X
X
Test mode selection:
0x00
Enables digital test modes
(global).
000 = disable test modes (default),
001 = enable digital sine test mode,
010 = reserved
011 = enable channel ID test mode
(16-bit data = digital ramp (7 bits) +
reserved bit (0) + Channel ID
(3 bits) +
chip address (5 bits),
100 = enable analog test tone,
101 = reserved,
110 = reserved,
111 = reserved
0x11C RESERVED_11C
0x11D RESERVED_11D
0x11E RESERVED_11E
0x11F RESERVED_11F
0x120 CW_TEST_TONE
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0x00
0x00
0x00
0x00
0x00
Reserved.
Reserved.
Reserved.
Reserved.
0
0
0
0
0
0
CW I/Q
output swap: cancel-
0 = disable
(default),
1 = enable
LNA offset
LNA offset cancellation CW analog test tone 0
Sets the frequency of the
analog test tone to fLO in
CW Doppler mode;
enables I/Q output swap;
LNA offset cancellation
control (global).
transconductance:
00 = 0.5 mS (default),
01 = 1.0 mS,
override for
Register 0x116
< Bits[1:0] >
lation:
0 = enable
(default),
1 = disable
10 = 1.5 mS,
11 = 2.0 mS
00 = disable override
(default)
01 = set analog test
tone frequency to fLO
1X = set analog test
tone frequency to dc
0x180 RESERVED_180
0x181 RESERVED_181
0x182 PLL_STARTUP
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
0
1
1
0
0
0x87
0x00
0x02
Reserved.
Reserved.
PLL auto configure:
0 = disable (default),
1 = enable
PLL control (global).
0x183 RESERVED_183
0x184 RESERVED_184
0x186 RESERVED_186
0x187 RESERVED_187
0x188 START_CODE_EN
0
0
1
0
0
0
0
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
1
0
0
1
0
1
0
0
1
0
1
0
0
1
0
0
0
0x07
0x00
Reserved.
Reserved.
0xAE Reserved.
0x20
0x01
Reserved.
Start code
identifier:
0 = disable,
1 = enable
(default)
Enables start code
identifier (global).
0x189 RESERVED_189
0x18A RESERVED_18A
0
0
0
0
0
0
0
0
0
0
0
0x00
0x00
0x27
0x72
0x10
0x00
0x18
0x00
Reserved.
0
0
0
0
0
Reserved.
0x18B START_CODE_MSB B15
0x18C START_CODE_LSB B7
B14
B6
0
B13
B5
0
B12
B4
1
B11
B3
0
B10
B2
0
B9
B1
0
B8
B0
0
Start code MSB (global).
Start code LSB (global).
Reserved.
0x190 RESERVED_190
0x191 RESERVED_191
0x192 RESERVED_192
0x193 RESERVED_193
0x194 RESERVED_194
0x195 RESERVED_195
0x196 RESERVED_196
0x197 RESERVED_197
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Reserved.
0
0
1
1
0
0
0
Reserved.
0
0
0
0
0
0
0
Reserved.
0
0
1
1
1
0
0
0x1C Reserved.
0
0
0
0
0
0
0
0x00
0x18
0x00
Reserved.
Reserved.
Reserved.
0
0
1
1
0
0
0
0
0
0
0
0
0
0
Rev. A | Page 45 of 47
AD9674
Data Sheet
Addr.
(Hex) Register Name
Default
Value Comments
0x00 DCO frequency control
Bit 7 (MSB)
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0 (LSB)
0x198 CLOCK_DOUBLING 0
0
0
0
DCO frequency doubling/divider:
0000 = 1 (default),
0001 = 2,
(global).
0010 = 4,
0011 = 8,
0100 = 16,
0101 = 32,
0110 = 64,
0111 = 128,
1000 = 1/256,
1001 = 1/128,
1010 = 1/64,
1011 = 1/32,
1100 = 1/16,
1101 = 1/8,
1110 = 1/4,
1111 = 1/2
0x199 SAMPLE_CLOCK_ Enables clocks per
0
0
0
0
0
0
0
0x00
Enables FCO function
(global).
COUNTER
sample auto
calculation:
0 = off (default),
1 = on
0x19A DATA_OUTPUT_
INVERT
X
X
X
X
X
X
X
Inverts data 0x00
output:
0 =
Inverts DOUT signal
outputs (global).
noninverted
(default),
1 = inverted
0x19B SERIAL_FORMAT
X
Enables FCO Enables
for start code FCO for
Enables FCO
continuously:
0 = only
FCO signal rotate:
0x70
FCO signal controls
(global).
0000 = FCO signal aligned with DOUT signal,
0001 = FCO 1 bit before DOUT,
0010 = FCO 2 bits before DOUT,
…,
sample:
extra
sample at during
end of
burst:
0 = disable,
1 = enable
(default)
burst, 1 =
continuous
1101 = FCO 3 bits after DOUT,
1110 = FCO 2 bits after DOUT,
1111 = FCO 1 bit after DOUT
0 = disable, (default)
1 = enable
(default)
0x19C RESERVED_19C
0x19D RESERVED_19D
0x19E RESERVED_19E
0x19F RESERVED_19F
0x1A0 RESERVED_1A0
0x1A1 RESERVED_1A1
Profile Memory Registers
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0x10
0x00
0x10
0x00
0x00
0x00
Reserved.
Reserved.
Reserved.
Reserved.
Reserved.
Reserved.
0xF00 Profile memory
to
32 × 64 bits
0x00
Vector profile memory
(global).
0xFFF
Set the speed mode in Register 0x002 and write to Register 0x0FF
at the beginning of the setup of the SPI writes after the device is
powered up to avoid rewriting other registers after Register 0x0FF
is written.
MEMORY MAP REGISTER DESCRIPTIONS
For more information about the SPI memory map and other
functions, consult the AN-877 Application Note, Interfacing
to High Speed ADCs via SPI.
Profile Index and Manual TX_TRIG (Register 0x10C)
Transfer (Register 0x0FF)
The vector profile is selected using the profile index in
All registers except Register 0x002 update as soon as they are
written. Writing to Register 0x0FF (the value written is don’t
care) initializes and updates the speed mode (Address 0x002)
and resets all other registers to their default values (analog and
ADC registers only, and not JESD204B registers, Register 0x000
or Register 0x002).
Register 0x10C, Bits[4:0]. The manual TX_TRIG control in Bit 5
generates a TX_TRIG signal internal to the device. This signal
is asynchronous to the ADC sample clock. Therefore, it cannot
be used to align the data output or initiate advanced power mode
across multiple devices in the system. The external pin driven
TX_TRIG control is recommended for systems that require
synchronization of these features across multiple AD9674 devices.
Rev. A | Page 46 of 47
Data Sheet
AD9674
OUTLINE DIMENSIONS
10.10
10.00 SQ
9.90
A1 BALL
CORNER
A1 BALL
CORNER
12 11 10
9
8
7
6
5
4
3
2
1
A
B
C
D
E
F
8.80
BSC SQ
G
H
J
0.80
K
L
M
0.60
REF
TOP VIEW
DETAIL A
BOTTOM VIEW
*
1.40 MAX
0.65 MIN
DETAIL A
0.25 MIN
0.50
0.45
0.40
COPLANARITY
0.12
SEATING
PLANE
BALL DIAMETER
*
COMPLIANT WITH JEDEC STANDARDS MO-275-EEAB-1
WITH THE EXCEPTION OF PACKAGE HEIGHT.
Figure 55. 144-Ball Chip Scale Package, Ball Grid Array [CSP_BGA]
(BC-144-1)
Dimensions shown in millimeters
ORDERING GUIDE
Model1
Temperature Range
Package Description
Package Option
BC-144-1
AD9674KBCZ
AD9670EBZ
0°C to 85°C
144-Ball Chip Scale Package, Ball Grid Array [CSP_BGA]
Evaluation Board
1 Z = RoHS Compliant Part.
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registered trademarks are the property of their respective owners.
D11293-0-1/16(A)
Rev. A | Page 47 of 47
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