LT5568EUF_技术文档

LT5568

700MHz – 1050MHz High

Linearity Direct Quadrature

Modulator

U

DESCRIPTIO

FEATURES

The LT^®5568 is a direct I/Q modulator designed for high

performance wireless applications, including wireless

infrastructure. It allows direct modulation of an RF signal

using differential baseband I and Q signals. It supports

PHS, GSM, EDGE, TD-SCDMA, CDMA, CDMA2000, W-

CDMA, and other systems. It may also be conﬁgured

as an image reject upconverting mixer, by applying

90° phase-shifted signals to the I and Q inputs. The I/Q

baseband inputs consist of voltage-to-current converters

that in turn drive double-balanced mixers. The outputs of

these mixers are summed and applied to an on-chip RF

transformer, which converts the differential mixer signals

to a 50Ω single-ended output. The four balanced I and Q

baseband input ports are intended for DC coupling from a

source with a common mode voltage level of about 0.5V.

The LO path consists of an LO buffer with single-ended

input, and precision quadrature generators that produce

the LO drive for the mixers. The supply voltage range is

4.5V to 5.25V.

■

Frequency Range: 700MHz to 1050MHz

■

High OIP3: +22.9dBm at 850MHz

■

Low Output Noise Floor at 5MHz Offset:

No RF: –160.3dBm/Hz

P

OUT

= 4dBm: –154dBm/Hz

■

3-Ch CDMA2000 ACPR: –71.4dBc at 850MHz

Integrated LO Buffer and LO Quadrature Phase

Generator

■

50Ω AC-Coupled Single-Ended LO and RF Ports

50Ω DC Interface to Baseband Inputs

Low Carrier Leakage: –43dBm at 850MHz

High Image Rejection: –46dBc at 850MHz

16-Lead 4mm × 4mm QFN Package

U

APPLICATIO S

■

Infrastructure Tx for Cellular Bands

■

Image Reject Up-Converters for Cellular Bands

■

Low-Noise Variable Phase-Shifter for 700MHz to

1050MHz Local Oscillator Signals

RFID Reader

, LTC and LT are registered trademarks of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

■

U

TYPICAL APPLICATIO

CDMA2000 ACPR, AltCPR and Noise vs RF

Output Power at 850MHz for 1 and 3 Carriers

700MHz to 1050MHz Direct Conversion Transmitter Application

–50

–60

–70

–80

–90

–125

–135

–145

–155

5V

100nF

x2

DOWNLINK TEST MODEL 64 DPCH

V

1-CH.

ACPR

CC

LT5568

RF = 700MHz

TO 1050MHz

I-DAC

V-I

I-CHANNEL

3-CH. ACPR

PA

0°

EN

90°

3-CH. AltCPR

1-CH. AltCPR

1-CH. NOISE

BALUN

Q-CHANNEL

V-I

Q-DAC

3-CH. NOISE

5568 TA01

BASEBAND

GENERATOR

–165

VCO/SYNTHESIZER

–30

–25

–20

–15

–10

–5

RF OUTPUT POWER PER CARRIER (dBm)

5568 TA02

5568f

1

LT5568

W W U W

U

W

U

ABSOLUTE AXI U RATI GS

PACKAGE/ORDER I FOR ATIO

(Note 1)

TOP VIEW

Supply Voltage.........................................................5.5V

Common Mode Level of BBPI, BBMI and

BBPQ, BBMQ .......................................................2.5V

Operating Ambient Temperature

16 15 14 13

EN

GND

LO

1

2

3

4

12 GND

11 RF

17

(Note 2) ............................................... –40°C to 85°C

Storage Temperature Range................... –65°C to 125°C

Voltage on any Pin

GND

10

9

GND

5

6

7

8

Not to Exceed...................... –500mV to V + 500mV

CC

UF PACKAGE

16-LEAD (4mm × 4mm) PLASTIC QFN

= 125°C, θ = 37°C/W

T

JMAX

JA

EXPOSED PAD (PIN 17) IS GROUND, MUST BE SOLDERED TO PCB

ORDER PART NUMBER

UF PART MARKING

5568

LT5568EUF

Order Options Tape and Reel: Add #TR

Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF

Lead Free Part Marking: http://www.linear.com/leadfree/

Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges.

ELECTRICAL CHARACTERISTICS

V_CC= 5V, EN = High, T_A= 25°C, f_LO= 850MHz, f_RF= 852MHz, P_LO= 0dBm.

BBPI, BBMI, BBPQ, BBMQ inputs 0.54V_DC, Baseband Input Frequency = 2MHz, I&Q 90° shifted (upper side-band selection).

P_{RF, OUT}= –10dBm, unless otherwise noted. (Note 3)

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

RF Output (RF)

f

RF Frequency Range

–3dB Bandwidth

–1dB Bandwidth

0.6 to 1.2

0.7 to 1.05

GHz

RF

S

RF Output Return Loss

RF Output Noise Floor

EN = High (Note 6)

EN = Low (Note 6)

–14

–12

dB

22, ON

22, OFF

NFloor

No Input Signal (Note 8)

–160.3

–154

dBm/Hz

P

= 4dBm (Note 9)

= 4dBm (Note 10)

OUT

G

Conversion Power Gain

Conversion Voltage Gain

Absolute Output Power

3 • LO Conversion Gain Difference

Output 1dB Compression

Output 2nd Order Intercept

Output 3rd Order Intercept

Image Rejection

P

/P

–9

–6.8

–2.8

–23

8.3

–3

dB

P

OUT IN, I&Q

20 • Log (V

/V

)

V

OUT, 50Ω IN, DIFF, I or Q

P

1V

CW Signal, I and Q

dBm

dB

OUT

P-P DIFF

G

(Note 17)

(Note 7)

3LO vs LO

OP1dB

OIP2

OIP3

IR

dBm

dBc

(Notes 13, 14)

(Notes 13, 15)

(Note 16)

63

22.9

–46

LOFT

Carrier Leakage

(LO Feedthrough)

EN = High, P = 0dBm (Note 16)

–43

–65

dBm

LO

EN = Low, P = 0dBm (Note 16)

LO

5568f

2

LT5568

ELECTRICAL CHARACTERISTICS

V_CC= 5V, EN = High, T_A= 25°C, f_LO= 850MHz, f_RF= 852MHz, P_LO= 0dBm.

BBPI, BBMI, BBPQ, BBMQ inputs 0.54V_DC, Baseband Input Frequency = 2MHz, I&Q 90° shifted (upper side-band selection).

P_{RF, OUT}= –10dBm, unless otherwise noted. (Note 3)

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

LO Input (LO)

f

LO Frequency Range

0.6 to 1.2

0

GHz

dBm

dB

LO

P

S

LO Input Power

–10

5

LO

LO Input Return Loss

EN = High (Note 6)

EN = Low (Note 6)

(Note 5) at 850MHz

–11.4

–2.7

12.7

11, ON

11, OFF

LO Input Return Loss

dB

NF

LO Input Referred Noise Figure

LO to RF Small Signal Gain

LO Input 3rd Order Intercept

dB

LO

G

23.8

dB

LO

IIP3

–11.5

dBm

LO

Baseband Inputs (BBPI, BBMI, BBPQ, BBMQ)

BW

Baseband Bandwidth

–3dB Bandwidth

(Note 4)

380

0.54

48

MHz

V

BB

V

DC Common Mode Voltage

Single-Ended Input Resistance

Carrier Feedthrough on BB

Input 1dB Compression Point

I/Q Absolute Gain Imbalance

I/Q Absolute Phase Imbalance

CMBB

Ω

R

(Note 4)

IN, SE

P

OUT

= 0 (Note 4)

–38

4.3

dBm

LO2BB

IP1dB

Differential Peak-to-Peak (Notes 7, 18)

V

P-P, DIFF

ΔG

0.07

0.45

dB

I/Q

Δϕ

Deg

Power Supply (V

)

CC

V

Supply Voltage

4.5

80

5

5.25

165

50

V

mA

μA

μs

CC

I

t

Supply Current

EN = High

117

CC, ON

CC, OFF

ON

Supply Current, Sleep Mode

Turn-On Time

EN = 0V

EN = Low to High (Note 11)

EN = High to Low (Note 12)

0.3

1.4

Turn-Off Time

μs

OFF

Enable (EN), Low = Off, High = On

Enable

Input High Voltage

Input High Current

EN = High

EN = 5V

1.0

V

230

0

μA

Sleep

Input Low Voltage

Input Low Current

EN = Low

EN = 0V

0.5

V

μA

Note 1: Absolute Maximum Ratings are those values beyond which the life

of a device may be impaired.

Note 10: At 5MHz offset from the CW signal frequency.

Note 11: RF power is within 10% of ﬁnal value.

Note 2: Speciﬁcations over the –40°C to 85°C temperature range are

assured by design, characterization and correlation with statistical process

controls.

Note 3: Tests are performed as shown in the conﬁguration of Figure 7.

Note 4: On each of the four baseband inputs BBPI, BBMI, BBPQ and

Note 12: RF power is at least 30dB lower than in the ON state.

Note 13: Baseband is driven by 2MHz and 2.1MHz tones. Drive level is set

in such a way that the two resulting RF tones are –10dBm each.

Note 14: IM2 measured at LO frequency + 4.1MHz.

Note 15: IM3 measured at LO frequency + 1.9MHz and LO frequency +

2.2MHz.

Note 16: Amplitude average of the characterization data set without image

or LO feedthrough nulling (unadjusted).

BBMQ.

Note 5: V(BBPI) – V(BBMI) = 1V , V(BBPQ) – V(BBMQ) = 1V

.

DC

Note 6: Maximum value within –1dB bandwidth.

Note 7: An external coupling capacitor is used in the RF output line.

Note 8: At 20MHz offset from the LO signal frequency.

Note 9: At 20MHz offset from the CW signal frequency.

Note 17: The difference in conversion gain between the spurious signal at

f = 3 • LO – BB versus the conversion gain at the desired signal at f = LO +

BB for BB = 2MHz and LO = 850MHz.

Note 18: The input voltage corresponding to the output P1dB.

5568f

3

LT5568

U W

V_CC= 5V, EN = High, T_A= 25°C, f_LO= 850MHz,

_LO= 0dBm. BBPI, BBMI, BBPQ, BBMQ inputs 0.54V_DC, Baseband Input Frequency f_BB= 2MHz, I&Q 90° shifted. f_RF= f_BB+ f_LO(upper

TYPICAL PERFOR A CE CHARACTERISTICS

P

sideband selection). P_{RF, OUT}= –10dBm (–10dBm/tone for 2-tone measurements), unless otherwise noted. (Note 3)

RF Output Power vs LO Frequency

at 1V_P-PDifferential Baseband Drive

Supply Current vs Supply Voltage

Voltage Gain vs LO Frequency

140

130

120

110

100

–4

–6

0

–2

85°C

25°C

–8

–10

–12

–14

–4

–6

5V, –40°C

5V, 25°C

5V, –40°C

5V, 25°C

–8

–40°C

5V, 85°C

4.5V, 25°C

5.5V, 25°C

4.5V, 25°C

5.5V, 25°C

–10

4.5

5

5.5

550 650 750 850 950 1050 1150 1250

LO FREQUENCY (MHz)

SUPPLY VOLTAGE (V)

LO FREQUENCY (MHz)

5568 G03

5568 G02

5568 G01

Output 1dB Compression

vs LO Frequency

Output IP3 vs LO Frequency

Output IP2 vs LO Frequency

26

24

70

65

60

55

50

10

8

f

= 2MHz

= 2.1MHz

BB, 1

BB, 2

f

= f

+ f

IM2 BB, 1 BB, 2 LO

= 2MHz

BB, 1

BB, 2

= 2.1MHz

22

20

18

16

6

5V, –40°C

5V, 25°C

5V, –40°C

5V, 25°C

5V, –40°C

5V, 25°C

4

5V, 85°C

4.5V, 25°C

5.5V, 25°C

4.5V, 25°C

5.5V, 25°C

4.5V, 25°C

5.5V, 25°C

2

550 650 750 850 950 1050 1150 1250

LO FREQUENCY (MHz)

5568 G04

5568 G06

5568 G05

LO Feedthrough to RF Output

vs LO Frequency

2 • LO Leakage to RF Output

vs 2 • LO Frequency

3 • LO Leakage to RF Output

vs 3 • LO Frequency

–40

–42

–44

–46

–48

–40

–45

–50

–55

–60

–40

–45

–50

–55

–60

–65

5V, –40°C

5V, 25°C

5V, 85°C

4.5V, 25°C

5.5V, 25°C

5V, –40°C

5V, 25°C

5V, –40°C

5V, 25°C

5V, 85°C

4.5V, 25°C

5.5V, 25°C

4.5V, 25°C

5.5V, 25°C

550 650 750 850 950 1050 1150 1250

LO FREQUENCY (MHz)

1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5

2 • LO FREQUENCY (GHz)

1.65 1.95 2.25 2.55 2.85 3.15 3.45 3.75

3 • LO FREQUENCY (GHz)

5568 G07

5568 G08

5568 G09

5568f

4

LT5568

U W

TYPICAL PERFOR A CE CHARACTERISTICS

V_CC= 5V, EN = High, T_A= 25°C, f_LO= 850MHz,

_LO= 0dBm. BBPI, BBMI, BBPQ, BBMQ inputs 0.54V_DC, Baseband Input Frequency f_BB= 2MHz, I&Q 90° shifted. f_RF= f_BB+ f_LO(upper

sideband selection). P_{RF, OUT}= –10dBm (–10dBm/tone for 2-tone measurements), unless otherwise noted. (Note 3)

P

LO and RF Port Return Loss

vs RF Frequency

Noise Floor vs RF Frequency

Image Rejection vs LO Frequency

–160

–161

–162

–163

–164

0

–10

–20

–30

–40

–30

–35

–40

–45

–50

LO PORT, EN = LOW

f

= 850MHz

5V, –40°C

5V, 25°C

LO

(FIXED)

LO PORT, EN = HIGH,

= 0dBm

5V, 85°C

P

LO

4.5V, 25°C

5.5V, 25°C

RF PORT,

EN = LOW

5V, –40°C

5V, 25°C

LO PORT,

EN = HIGH,

5V, 85°C

P

= –10dBm

LO

RF PORT, EN = HIGH, No LO

4.5V, 25°C

5.5V, 25°C

RF PORT, EN = HIGH, P = 0dBm

LO

550 650 750 850 950 1050 1150 1250

RF FREQUENCY (MHz)

LO FREQUENCY (MHz)

5568 G12

5568 G10

5568 G11

Absolute I/Q Gain Imbalance

vs LO Frequency

Absolute I/Q Phase Imbalance

vs LO Frequency

Voltage Gain vs LO Power

–4

0.2

0.1

0

4

3

2

1

0

5V, –40°C

5V, 25°C

5V, –40°C

5V, 25°C

–6

–8

5V, 85°C

4.5V, 25°C

5.5V, 25°C

4.5V, 25°C

5.5V, 25°C

–10

–12

–14

–16

5V, –40°C

5V, 25°C

5V, 85°C

4.5V, 25°C

5.5V, 25°C

–20 –16 –12

–8

–4

0

4

8

550 650 750 850 950 1050 1150 1250

LO INPUT POWER (dBm)

LO FREQUENCY (MHz)

5568 G15

5568 G13

5568 G14

RF CW Output Power, HD2 and HD3 vs

Output IP3 vs LO Power

CW Baseband Voltage and Temperature

–10

–20

–30

–40

–50

–60

–70

–80

10

25

23

21

19

17

15

13

0

RF

–40°C

85°C

–40°C

85°C

25°C

–10

–20

–30

–40

–50

–60

25°C

HD3

–40°C

HD2

5V, –40°C

5V, 25°C

85°C

5V, 85°C

f

= 2MHz

= 2.1MHz

4.5V, 25°C

5.5V, 25°C

BB, 1

BB, 2

0

1

2

3

4

5

–20 –16 –12

–8

–4

0

4

8

I AND Q BASEBAND VOLTAGE (V

)

P–P, DIFF

LO INPUT POWER (dBm)

5568 G16

HD2 = MAX POWER AT f + 2 • f OR f – 2 • f

LO

BB

LO

BB

HD3 = MAX POWER AT f + 3 • f OR f – 3 • f

5568 G17

LO

BB

LO

5568f

5

LT5568

U W

V_CC= 5V, EN = High, T_A= 25°C, f_LO= 850MHz,

_LO= 0dBm. BBPI, BBMI, BBPQ, BBMQ inputs 0.54V_DC, Baseband Input Frequency f_BB= 2MHz, I&Q 90° shifted. f_RF= f_BB+ f_LO(upper

TYPICAL PERFOR A CE CHARACTERISTICS

P

sideband selection). P_{RF, OUT}= –10dBm (–10dBm/tone for 2-tone measurements), unless otherwise noted. (Note 3)

RF CW Output Power, HD2 and

LO Feedthrough to RF Output

vs CW Baseband Voltage

Image Rejection

HD3 vs CW Baseband Voltage

and Supply Voltage

vs CW Baseband Voltage

–10

–20

–30

–40

–50

–60

–70

–80

10

0

–36

–38

–40

–42

–44

–35

–40

–45

–50

–55

5V, –40°C

5V, 25°C

5V, –40°C

5V, 25°C

RF

5V, 85°C

5V

4.5V

4.5V, 25°C

5.5V, 25°C

4.5V, 25°C

5.5V, 25°C

–10

–20

–30

–40

–50

–60

HD3

5V

4.5V

HD2

5.5V

0

1

2

3

4

5

)

0

1

2

3

4

5

)

0

1

2

3

4

5

)

I AND Q BASEBAND VOLTAGE (V

P–P, DIFF

I AND Q BASEBAND VOLTAGE (V

P–P, DIFF

5568 G19

HD2 = MAX POWER AT f + 2 • f OR f – 2 • f

5568 G20

LO

BB

LO

BB

HD3 = MAX POWER AT f + 3 • f OR f – 3 • f

LO

BB

LO

5568 G18

RF Two-Tone Power (Each Tone),

IM2 and IM3 vs Baseband Voltage

and Supply Voltage

RF Two-Tone Power (Each Tone),

IM2 and IM3 vs Baseband Voltage

and Temperature

Gain Distribution

10

0

10

0

60

50

40

30

20

10

0

–40°C

25°C

85°C

RF

–40°C

25°C

85°C

4.5V

–10

–20

–30

–40

–50

–60

–70

–80

–10

–20

–30

–40

–50

–60

–70

–80

4.5V

5V, 5.5V

–40°C

5V, 5.5V

25°C

85°C

25°C

IM3

5V

IM3

4.5V

–40°C

IM2

5.5V

IM2

85°C

f

= 2MHz, 2.1MHz, 0°

= 2MHz, 2.1MHz, 90°

f

= 2MHz, 2.1MHz, 0°

= 2MHz, 2.1MHz, 90°

BBI

BBQ

BBI

BBQ

0.1

1

10

0.1

1

10

)

–8

–7

–6.5

–6

–7.5

I AND Q BASEBAND VOLTAGE (V

)

I AND Q BASEBAND VOLTAGE (V

P–P, DIFF, EACH TONE

GAIN (dB)

5568 G23

IM2 = POWER AT f + 4.1MHz

LO

IM3 = MAX POWER AT f + 1.9MHz OR f + 2.2MHz

LO

Noise Floor Distribution

LO Leakage Distribution

Image Rejection Distribution

60

50

40

30

20

10

0

40

30

20

10

0

50

40

30

20

10

0

f

= 870MHz

–40°C

25°C

85°C

P

= –10dBm

LO

–40°C

25°C

85°C

–40°C

25°C

85°C

V = 800mV

BB P-P,DIFF

NOISE

NO BASEBAND

APPLIED

–160.8

–160

–159.6

–159.2

–54

–46

–42

–38

–34

–160.4

–50

< –60

–52

–48

–44

–56

NOISE FLOOR (dBm/Hz)

LO LEAKAGE (dBm)

IMAGE REJECTION (dBc)

5568 G26

5568 G24

5568 G25

5568f

6

LT5568

U

PI FU CTIO S

BBPQ,BBMQ(Pins7,5):BasebandInputsfortheQ-chan-

nel, each 50Ω input impedance. Internally biased at about

0.54V. Applied voltage must stay below 2.5V.

EN (Pin 1): Enable Input. When the enable pin voltage is

higher than 1V, the IC is turned on. When the input voltage

is less than 0.5V, the IC is turned off.

V

(Pins 8, 13): Power Supply. Pins 8 and 13 are con-

GND (Pins 2, 4, 6, 9, 10, 12, 15): Ground. Pins 6, 9, 15

and 17 (exposed pad) are connected to each other inter-

nally. Pins 2 and 4 are connected to each other internally

and function as the ground return for the LO signal. Pins

10 and 12 are connected to each other internally and

function as the ground return for the on-chip RF balun.

For best RF performance, pins 2, 4, 6, 9, 10, 12, 15 and

the Exposed Pad 17 should be connected to the printed

circuit board ground plane.

CC

nected to each other internally. It is recommended to use

0.1μF capacitors for decoupling to ground on each of

these pins.

RF (Pin 11): RF Output. The RF output is an AC-coupled

single-ended output with approximately 50Ω output im-

pedance at RF frequencies. Externally applied DC voltage

should be within the range –0.5V to V + 0.5V in order

to avoid turning on ESD protection diodes.

CC

LO(Pin3):LOInput.TheLOinputisanAC-coupledsingle-

ended input with approximately 50Ω input impedance at

RF frequencies. Externally applied DC voltage should be

BBPI, BBMI (Pins 14, 16): Baseband Inputs for the

I-channel,eachwith50Ωinputimpedance.Internallybiased

at about 0.54V. Applied voltage must stay below 2.5V.

within the range –0.5V to V + 0.5V in order to avoid

CC

Exposed Pad (Pin 17): Ground. This pin must be soldered

to the printed circuit board ground plane.

turning on ESD protection diodes.

5568f

7

LT5568

W

BLOCK DIAGRA

V

CC

8

13

LT5568

BBPI 14

BBMI 16

V-I

11 RF

0°

90°

BALUN

BBPQ

BBMQ

7

5

1

EN

2

4

6

9

3

10

12

15

17

5568 BD

GND

LO

GND

U

W U U

APPLICATIO S I FOR ATIO

The LT5568 consists of I and Q input differential voltage-

to-current converters, I and Q up-conversion mixers, an

RF output balun, an LO quadrature phase generator and

LO buffers.

External I and Q baseband signals are applied to the dif-

ferential baseband input pins, BBPI, BBMI, and BBPQ,

BBMQ.Thesevoltagesignalsareconvertedtocurrentsand

translated to RF frequency by means of double-balanced

up-converting mixers. The mixer outputs are combined

in an RF output balun, which also transforms the output

impedance to 50Ω. The center frequency of the resulting

RF signal is equal to the LO signal frequency. The LO input

drives a phase shifter which splits the LO signal into in-

phaseandquadratureLOsignals.TheseLOsignalsarethen

applied to on-chip buffers which drive the up-conversion

mixers. Both the LO input and RF output are single-ended,

50Ω-matched and AC coupled.

LT5568

RF

= 5V

C

V

CC

BALUN

FROM

Q

LOMI

CM

LOPI

R1A

25Ω

R1B

23Ω

R2B

23Ω

R2A

25Ω

BBPI

R3

R4

12pF

Baseband Interface

V

REF

= 540mV

BBMI

Thebasebandinputs(BBPI,BBMI),(BBPQ,BBMQ)present

adifferentialinputimpedanceofabout100Ω.Ateachofthe

fourbasebandinputs,aﬁrst-orderlowpassﬁlterusing25Ω

5568 F01

GND

Figure 1. Simpliﬁed Circuit Schematic of the LT5568

(Only I-Half is Drawn)

5568f

8

LT5568

U

W U U

APPLICATIO S I FOR ATIO

and 12pF to ground is incorporated (see Figure 1), which Thebasebandinputsshouldbedrivendifferentially;other-

limits the baseband bandwidth to approximately 330MHz wise, the even-order distortion products will degrade the

(–1dB point). The common mode voltage is about 0.54V overall linearity severely. Typically, a DAC will be the signal

and is approximately constant over temperature.

source for the LT5568. Reconstruction ﬁlters should be

placedbetweentheDACoutputandtheLT5568’sbaseband

inputs.InFigure3,anexampleinterfaceschematicshowsa

commonlyusedDACoutputinterfacefollowedbyapassive

Itisimportantthattheappliedcommonmodevoltagelevel

of the I and Q inputs is about 0.54V in order to properly

bias the LT5568. Some I/Q test generators allow setting

the common mode voltage independently. In this case, the

common mode voltage of those generators must be set

to 0.27V to match the LT5568 internal bias, because for

DC signals, there is no –6dB source-load voltage division

(see Figure 2).

th

5 order ladder ﬁlter. The DAC in this example sources

a current from 0mA to 20mA. The interface may be DC

coupled. This allows adjustment of the DAC’s differential

outputcurrenttominimizetheLOfeedthrough.Optionally,

transformer T1 can be inserted to improve the current

balance in the BBPI and BBMI pins. This will improve the

2nd order distortion performance (OIP2).

50Ω

48Ω

The maximum single sideband CW RF output power at

850MHz using both I and Q channels with the conﬁgura-

tion shown in Figure 3 is about –3dBm. The maximum

CW output power can be increased by connecting load

resistors R5 and R6 to –5V instead of GND, and changing

their values to 550Ω. In that case, the maximum single

sideband CW RF output power at 850MHz will be about

+2dBm. In addition, the ladder ﬁlter component values

require adjustment for a higher source impedance.

0.27V

0.54V

DC

+

DC

0.54V

DC

–

50Ω

GENERATOR

LT5568

5568 F02

Figure 2. DC Voltage Levels for a Generator Programmed at

0.27V_DCfor a 50Ω Load and the LT5568 as a Load

V

= 5V

CC

LT5568

LOPI

RF = –3dBm, MAX

BALUN

C

LOMI

CM

R1

R2

0.5V

L1A

L2A

45Ω

BBPI

T1

1:1

0mA to 20mA

R5, 50Ω

C1

R6, 50Ω

R3

33Ω

R4

33Ω

DAC

C2

L1B

C3

L2B

V

REF

= 500mV

15mA

GND

0.5V

BBMI

5568 F03

GND

Figure 3. LT5568 5^thOrder Filtered Baseband Interface with Common DAC (Only I-Channel is Shown)

5568f

9

LT5568

U

W U U

APPLICATIO S I FOR ATIO

Table 1. LO Port Input Impedance vs Frequency for EN = High

and P_LO= 0dBm

LO Section

The internal LO input ampliﬁer performs single-ended to

differential conversion of the LO input signal. Figure 4

shows the equivalent circuit schematic of the LO input.

Frequency

MHz

Input Impedance

S

11

Ω

Mag

Angle

95.0

500

600

47.5 + j12.1

59.4 + j8.4

0.126

0.115

0.140

0.185

0.232

0.252

0.258

0.297

37.8

V

CC

700

800

900

1000

1100

1200

66.2 – j1.14

67.2 – j13.4

61.1 – j23.9

53.3 – j26.8

48.2 – j26.1

42.0 – j27.4

–3.41

–31.7

–53.2

–68.7

–79.4

–90.0

20pF

LO

INPUT

51Ω

5568 F04

If the part is in shutdown mode, the input impedance of

the LO port will be different. The LO input impedance for

EN = Low is given in Table 2.

Table 2. LO Port Input Impedance vs Frequency for EN = Low and

P_LO= 0dBm

Figure 4. Equivalent Circuit Schematic of the LO Input

Theinternal,differentialLOsignalisthensplitintoin-phase

and quadrature (90° phase shifted) signals that drive LO

buffer sections. These buffers drive the double balanced

I and Q mixers. The phase relationship between the LO

input and the internal in-phase LO and quadrature LO

signals is ﬁxed, and is independent of start-up conditions.

The internal phase shifters are designed to deliver accu-

rate quadrature signals. For LO frequencies signiﬁcantly

below 600MHz or above 1GHz, however, the quadrature

accuracy will diminish, causing the image rejection to

degrade. The LO pin input impedance is about 50Ω, and

the recommended LO input power is 0dBm. For lower

LO input power, the gain, OIP2, OIP3 and noise ﬂoor at

Frequency

MHz

Input Impedance

S

11

Ω

Mag

Angle

85.4

49.8

19.6

–6.8

–29.6

–45.5

–65.6

–79.7

500

600

700

800

900

1000

1100

1200

33.6 + j41.3

59.8 + j69.1

140 + j89.8

225 – j62.6

92.9 – j128

39.8 – j95.9

22.8 – j72.7

16.0 – j57.3

0.477

0.539

0.606

0.659

0.704

0.735

0.755

0.763

P

A

= 4dBm will degrade, especially below –5dBm and at

RF

RF Section

T = 85°C. For high LO input power (e.g., +5dBm), the LO

Afterup-conversion,theRFoutputsoftheIandQmixersare

combined. An on-chip balun performs internal differential

tosingle-endedoutputconversion,whiletransformingthe

output signal impedance to 50Ω. Table 3 shows the RF

port output impedance vs frequency.

feedthroughwillincreasewithnoimprovementinlinearity

or gain. For lower LO input power, e.g., P = –5dBm, the

LO

image rejection improves (especially around 950MHz) at

the cost of 1.5dB degradation of the noise ﬂoor at P

=

RF

4dBm.HarmonicspresentontheLOsignalcandegradethe

imagerejectionbecausetheycanintroduceasmallexcess

phase shift in the internal phase splitter. For the second (at

1.7GHz) and third harmonics (at 2.55GHz) at –20dBc, the

resulting signal at the image frequency is about –56dBc

or lower, corresponding to an excess phase shift of much

less than 1 degree. For the second and third LO harmonics

at –10dBc, the introduced signal at the image frequency is

about –47dBc. Higher harmonics than the third will have

less impact. The LO return loss typically will be better than

11dB over the 700MHz to 1.05GHz range. Table 1 shows

the LO port input impedance vs frequency.

Table 3. RF Port Output Impedance vs Frequency for EN = High

and P_LO= 0dBm

Frequency

MHz

Input Impedance

S

22

Ω

Mag

Angle

164.2

141.3

117.5

90.6

–94.7

–117.0

–130.7

–141.6

500

600

700

800

900

1000

1100

1200

22.0 + j5.7

28.2 + j12.5

38.8 + j14.8

49.4 + j7.2

49.3 – j5.1

42.5 – j11.1

36.7 – j11.7

33.0 – j10.3

0.395

0.317

0.206

0.072

0.051

0.143

0.202

0.238

5568f

10

LT5568

U

W U U

APPLICATIO S I FOR ATIO

The RF output S with no LO power applied is given in Note that an ESD diode is connected internally from

22

Table 4.

the RF output to ground. For strong output RF signal

levels (higher than 3dBm), this ESD diode can degrade

the linearity performance if the 50Ω termination imped-

ance is connected directly to ground. To prevent this, a

coupling capacitor can be inserted in the RF output line.

This is strongly recommended during a 1dB compression

measurement.

Table 4. RF Port Output Impedance vs Frequency for EN = High

and No LO Power Applied

Frequency

MHz

Input Impedance

S

22

Ω

Mag

Angle

164.0

500

600

22.7 + j5.6

29.7 + j11.6

40.5 + j11.6

47.3 + j2.2

44.1 – j6.7

38.2 – j9.8

34.0 – j9.4

31.5 – j7.8

0.381

0.290

0.164

0.037

0.094

0.171

0.218

0.245

142.0

700

121.9

800

139.6

Enable Interface

900

–126.9

–133.9

–143.1

–151.6

Figure 6 shows a simpliﬁed schematic of the EN pin in-

terface. The voltage necessary to turn on the LT5568 is

1V. To disable (shut down) the chip, the enable voltage

must be below 0.5V. If the EN pin is not connected, the

chip is disabled. This EN = Low condition is assured by

the 75k on-chip pull-down resistor. It is important that

1000

1100

1200

For EN = Low the S is given in Table 5.

22

Table 5. RF Port Output Impedance vs Frequency for EN = Low

the voltage at the EN pin does not exceed V by more

CC

Frequency

MHz

Input Impedance

S

22

than 0.5V. If this should occur, the supply current could

be sourced through the EN pin ESD protection diodes,

which are not designed to carry the full supply current,

and damage may result.

Ω

Mag

Angle

164.9

142.5

118.1

87.4

500

600

21.2 + j5.4

26.6 + j12.5

36.6 + j16.6

49.2 + j11.6

52.9 – j2.0

46.4 – j11.2

39.3 – j13.2

34.4 – j12.1

0.409

0.340

0.241

0.116

0.034

0.121

0.188

0.231

700

800

900

–33.1

–101.1

–120.6

–133.8

1000

1100

1200

V

CC

V

CC

EN

75k

25k

21pF

RF

OUTPUT

7nH

1pF

51Ω

5568 F06

5568 F05

Figure 6. EN Pin Interface

Figure 5. Equivalent Circuit Schematic of the RF Output

5568f

11

LT5568

U

W U U

APPLICATIO S I FOR ATIO

Evaluation Board

R1 (optional) limits the EN pin current in the event that

the EN pin is pulled high while the V inputs are low. In

CC

Figure 7 shows the evaluation board schematic. A good

ground connection is required for the exposed pad. If this

is not done properly, the RF performance will degrade. Ad-

ditionally,theexposedpadprovidesheatsinkingforthepart

and minimizes the possibility of the chip overheating.

Figures 8 and 9 the silk screens and the PCB board layout

are shown.

J1

J2

BBIM

BBIP

V

CC

C2

16

BBMI GND BBPI

EN

15

14

13

100nF

R1

V

CC

100Ω

1

2

3

4

12

GND

RF

V

EN

CC

J3

11

10

9

RF

OUT

GND

LO

J4

LO

IN

LT5568

GND

17

BBMQ GND BBPQ

V

CC

5

6

7

8

C1

100nF

J5

J6

BBQM

GND

BBQP

BOARD NUMBER: DC966A

5568 F07

Figure 7. Evaluation Circuit Schematic

Figure 8. Component Side of Evaluation Board

Figure 9. Bottom Side of Evaluation Board

5568f

12

LT5568

U

W U U

APPLICATIO S I FOR ATIO

Application Measurements

ment. See Application Note 99. Consult the factory for

advice on the ACPR measurement, if needed.

TheLT5568isrecommendedforbase-stationapplications

usingvariousmodulationformats. Figure10showsatypi-

cal application. Figure 11 shows the ACPR performance

for CDMA2000 using 1- and 3-carrier modulation. Figures

12 and 13 illustrate the 1- and 3-carrier CDMA2000 RF

spectrum. To calculate ACPR, a correction is made for the

spectrum analyzer noise ﬂoor. If the output power is high,

theACPRwillbelimitedbythelinearityperformanceofthe

part. If the output power is low, the ACPR will be limited

by the noise performance of the part. In the middle, an

optimum ACPR is observed.

TheACPRperformanceissensitivetotheamplitudematch

of the BBIP and BBIM (or BBQP and BBQM) inputs. This

is because a difference in AC current amplitude will give

rise to a difference in amplitude between the even-order

harmonic products generated in the internal V-I converter.

As a result, they will not cancel out entirely. Therefore, it

is important to keep the currents in those pins exactly the

same (but of opposite sign). The current will enter the

LT5568’s common-base stage, and will ﬂow to the mixer

upper switches. This can be seen in Figure 1 where the

internal circuit of the LT5568 is drawn. For best results,

a high ohmic source is recommended; for example, the

Because of the LT5568’s very high dynamic range, the test

equipment can limit the accuracy of the ACPR measure-

–50

–60

–70

–80

–90

–125

–135

–145

–155

5V

100nF

DOWNLINK TEST MODEL 64 DPCH

3-CH. ACPR

V

CC 8, 13

1-CH.

ACPR

L5568

14

16

x2

RF = 700MHz

TO 1050MHz

I-DAC

V-I

I-CHANNEL

11

PA

0°

1

EN

90°

BALUN

3-CH. AltCPR

1-CH. AltCPR

1-CH. NOISE

Q-CHANNEL

V-I

7

5

Q-DAC

3-CH. NOISE

BASEBAND

GENERATOR

5568 F10

3

VCO/SYNTHESIZER

2, 4, 6, 9, 10, 12, 15, 17

–165

–30

–25

–20

–15

–10

–5

RF OUTPUT POWER PER CARRIER (dBm)

5568 F11

Figure 10. 700MHz to 1050MHz Direct

Conversion Transmitter Application

Figure 11. APCR, AltCPR and Noise

CDMA2000 Modulation

–30

–40

DOWNLINK TEST

DOWNLINK

TEST

MODEL 64

DPCH

–40

–50

–60

–70

–80

–90

MODEL 64 DPCH

–50

–60

–70

–80

UNCORRECTED

SPECTRUM

–90

UNCORRECTED

SPECTRUM

CORRECTED

SPECTRUM

–100

–110

–120

–130

–100

–110

–120

–130

CORRECTED

SPECTRUM

SPECTRUM ANALYSER

NOISE FLOOR

SPECTRUM ANALYSER NOISE FLOOR

846.25 847.75 849.25 850.75 852.25 853.75

844

846

848

850

852

856

RF FREQUENCY (MHz)

5568 F13

5568 F12

Figure 12. 1-Carrier CDMA2000 Spectrum

Figure 13. 3-Carrier CDMA2000 Spectrum

5568f

13

LT5568

U

W U U

APPLICATIO S I FOR ATIO

interface circuit drawn in Figure 3, modiﬁed by pulling match.Thesecondarycentertapshouldnotbeconnected,

resistors R5 and R6 to a –5V supply and adjusting their

whichallowssomevoltageswingifthereisasingle-ended

input impedance difference at the baseband pins. As a

result,bothcurrentswillbeequal.Thedisadvantageisthat

there is no DC coupling, so the LO feedthrough calibration

cannotbeperformedviatheBBconnections. Aftercalibra-

tion when the temperature changes, the LO feedthrough

and the image rejection performance will change. This is

illustrated in Figure 14. The LO feedthrough and image

rejection can also change as a function of the baseband

drive level, as is depicted in Figure 15. In Figures 16 and

17 the LO feedthrough and image rejection vs LO power

are shown.

values to 550Ω, with T1 omitted.

Another method to reduce current mismatch between

the currents ﬂowing in the BBIP and BBIM pins (or the

BBQP and BBQM pins) is to use a 1:1 transformer with

the two windings in the DC path (T1 in Figure 3). For DC,

the transformer forms a short, and for AC, the transformer

will reduce the common mode current component, which

forcesthetwocurrentstobebettermatched. Alternatively,

atransformerwith1:2impedanceratiocanbeused, which

gives a convenient DC separation between primary and

secondary in combination with the required impedance

–40

10

CALIBRATED WITH P = –10dBm

RF

–40°C

85°C

0

–10

–20

–30

–40

–50

–60

–70

–80

–90

P

RF

25°C

IMAGE REJECTION

–50

–60

–70

–80

–90

LOFT

IR

LO FEED-

THROUGH

–40°C

85°C

= 5V

EN = High

= 850MHz

V

f

= 5V

CC

V

f

= 2MHz, 0°

CC

BB, 1

BB, 0

f

= f + f

LO

= 2MHz, 0°

BBQ

= 850MHz

RF BB LO

= 2MHz, 90°

BBI

P

= 0dBm

= 2MHz, 90°+ϕ

f

= f + f

LO

RF BB LO

EN = High

40

60

TEMPERATURE (°C)

P

LO

25°C

LO = 0dBm

–40 –20

0

20

80

0

1

2

3

4

5

I AND Q BASEBAND VOLTAGE (V

)

5568 F14

P-P, DIFF

5568 F15

Figure 14. LO Feedthrough and Image Rejection

vs Temperature after Calibration at 25°C

Figure 15. LO Feedthrough and Image Rejection

vs Baseband Drive Voltage after Calibration at 25°C

–42

–25

f

LO

= 850MHz

f

= 850MHz

= –10dBm

LO

RF

P

–30

–35

–40

–45

–50

–55

–44

–46

–48

–50

5V, –40°C

5V, 25°C

5V, –40°C

5V, 25°C

5V, 85°C

4.5V, 25°C

5.5V, 25°C

4.5V, 25°C

5.5V, 25°C

–20 –16 –12 –8

–4

0

4

8

–20 –16 –12 –8

–4

0

4

8

LO INPUT POWER (dBm)

5568 G16

5568 G17

Figure 16. LO Feedthrough vs LO Power

Figure 17. Image Rejection vs LO Power

5568f

14

LT5568

U

PACKAGE DESCRIPTIO

UF Package

16-Lead Plastic QFN (4mm × 4mm)

(Reference LTC DWG # 05-08-1692)

0.72 0.05

4.35 0.05

2.90 0.05

2.15 0.05

(4 SIDES)

PACKAGE OUTLINE

0.30 0.05

0.65 BSC

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

BOTTOM VIEW—EXPOSED PAD

PIN 1 NOTCH R = 0.20 TYP

OR 0.35 × 45° CHAMFER

0.75 0.05

R = 0.115

TYP

4.00 0.10

(4 SIDES)

15

16

0.55 0.20

PIN 1

TOP MARK

(NOTE 6)

1

2

2.15 0.10

(4-SIDES)

(UF16) QFN 10-04

0.200 REF

0.30 0.05

0.65 BSC

0.00 – 0.05

NOTE:

1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGGC)

2. DRAWING NOT TO SCALE

3. ALL DIMENSIONS ARE IN MILLIMETERS

4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE

MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE

5. EXPOSED PAD SHALL BE SOLDER PLATED

6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION

ON THE TOP AND BOTTOM OF PACKAGE

5568f

InformationfurnishedbyLinearTechnologyCorporationisbelievedtobeaccurateandreliable.However,

no responsibility is assumed for its use. Linear Technology Corporation makes no representation that

the interconnection of its circuits as described herein will not infringe on existing patent rights.

15

LT5568

RELATED PARTS

PART NUMBER

Infrastructure

LT5511

DESCRIPTION

COMMENTS

High Linearity Upconverting Mixer

RF Output to 3GHz, 17dBm IIP3, Integrated LO Buffer

LT5512

DC to 3GHz High Signal Level Downconverting DC to 3GHz, 17dBm IIP3, Integrated LO Buffer

Mixer

LT5514

LT5515

LT5516

Ultralow Distortion, IF Ampliﬁer/ADC Driver

with Digitally Controlled Gain

850MHz Bandwidth, 47dBm OIP3 at 100MHz, 10.5dB to 33dB Gain Control Range

1.5GHz to 2.5GHz Direct Conversion Quadrature 20dBm IIP3, Integrated LO Quadrature Generator

Demodulator

0.8GHz to 1.5GHz Direct Conversion Quadrature 21.5dBm IIP3, Integrated LO Quadrature Generator

Demodulator

LT5517

LT5518

40MHz to 900MHz Quadrature Demodulator

21dBm IIP3, Integrated LO Quadrature Generator

1.5GHz to 2.4GHz High Linearity Direct

Quadrature Modulator

22.8dBm OIP3 at 2GHz, –158.2dBm/Hz Noise Floor, 50Ω Single-Ended LO and RF

Ports, 4-Ch W-CDMA ACPR = –64dBc at 2.14GHz

LT5519

LT5520

LT5521

LT5522

LT5524

LT5526

LT5527

LT5528

0.7GHz to 1.4GHz High Linearity Upconverting 17.1dBm IIP3 at 1GHz, Integrated RF Output Transformer with 50Ω Matching,

Mixer Single-Ended LO and RF Ports Operation

1.3GHz to 2.3GHz High Linearity Upconverting 15.9dBm IIP3 at 1.9GHz, Integrated RF Output Transformer with 50Ω Matching,

Mixer

Single-Ended LO and RF Ports Operation

10MHz to 3700MHz High Linearity

Upconverting Mixer

24.2dBm IIP3 at 1.95GHz, NF = 12.5dB, 3.15V to 5.25V Supply, Single-Ended LO

Port Operation

600MHz to 2.7GHz High Signal Level

Downconverting Mixer

4.5V to 5.25V Supply, 25dBm IIP3 at 900MHz, NF = 12.5dB, 50Ω Single-Ended RF

and LO Ports

Low Power, Low Distortion ADC Driver with

Digitally Programmable Gain

450MHz Bandwidth, 40dBm OIP3, 4.5dB to 27dB Gain Control

High Linearity, Low Power Downconverting

Mixer

3V to 5.3V Supply, 16.5dBm IIP3, 100kHz to 2GHz RF, NF = 11dB, I = 28mA,

CC

–65dBm LO-RF Leakage

400MHz to 3.7GHz High Signal Level

Downconverting Mixer

IIP3 = 23.5dBm and NF = 12.5dB at 1900MHz, 4.5V to 5.25V Supply, I = 78mA

CC

1.5GHz to 2.4GHz High Linearity Direct

Quadrature Modulator

21.8dBm OIP3 at 2GHz, –159.3dBm/Hz Noise Floor, 50Ω, 0.5V Baseband Interface,

DC

4-Ch W-CDMA ACPR = –66dBc at 2.14GHz

RF Power Detectors

LTC^®5505

RF Power Detectors with >40dB Dynamic

Range

300MHz to 3GHz, Temperature Compensated, 2.7V to 6V Supply

LTC5507

LTC5508

LTC5509

LTC5532

LT5534

100kHz to 1000MHz RF Power Detector

300MHz to 7GHz RF Power Detector

300MHz to 3GHz RF Power Detector

100kHz to 1GHz, Temperature Compensated, 2.7V to 6V Supply

44dB Dynamic Range, Temperature Compensated, SC70 Package

36dB Dynamic Range, Low Power Consumption, SC70 Package

300MHz to 7GHz Precision RF Power Detector Precision V

Offset Control, Adjustable Gain and Offset

OUT

50MHz to 3GHz Loq RF Power Detector with

60dB Dynamic Range

1dB Output Variation over Temperature, 38ns Response Time

LTC5536

Precision 600MHz to 7GHz RF Detector with

Fast Comparater

25ns Response Time, Comparator Reference Input, Latch Enable Input, –26dBm to

+12dBm Input Range

LT5537

Wide Dynamic Range Loq RF/IF Detector

Low Frequency to 800MHz, 83dB Dynamic Range, 2.7V to 5.25V Supply

High Speed ADCs

LTC2220-1

12-Bit, 185Msps ADC

Single 3.3V Supply, 910mW Consumption, 67.5dB SNR, 80dB SFDR, 775MHz Full

Power BW

LTC2249

LTC2255

14-Bit, 80Msps ADC

14-Bit, 125Msps ADC

Single 3V Supply, 222mW Consumption, 73dB SNR, 90dB SFDR

Single 3V Supply, 395mW Consumption, 72.4dB SNR, 88dB SFDR, 640MHz Full

Power BW

5568f

LT/TP 1005 500 • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

16

●

(408) 432-1900 FAX: (408) 434-0507 www.linear.com


型号：	LT5568EUF
厂家：	Linear
描述：	RF/Microwave Modulator/Demodulator, 700 MHz - 1050 MHz RF/MICROWAVE I/Q MODULATOR, 4 X 4 MM, PLASTIC, MO-220WGGC, QFN-16 射频微波
文件：	总16页 (文件大小：328K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LT5568EUF [Linear]

相关型号：

SI9130DB

SI9135LG-T1

SI9135LG-T1-E3

SI9135_11

SI9136_11

SI9130CG-T1-E3

SI9130LG-T1-E3

SI9130_11

SI9137

SI9137DB

SI9137LG

SI9122E