LT5571

1

5571f

RF OUTPUT POWER PER CARRIER (dBm)

–30

–70

–60

–10

5571 TA01b

–80

–90

–25

–20

–15

0

–5

–40

–50

–140

–130

–150

–160

–110

–120

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MODEL 64 DPCH

3-CH ACPR

1-CH

ACPR

3-CH AltCPR

1-CH AltCPR

3-CH NOISE

1-CH NOISE

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

620MHz – 1100MHz High

Linearity Direct Quadrature

Modulator

performance wireless applications, including wireless

infrastructure. It allows direct modulation of an RF signal

using differential baseband I and Q signals. It supports

RFID, GSM, EDGE, CDMA, CDMA2000, and other systems.

It may also be configured as an image reject upconvert-

ing mixer by applying 90° phase-shifted signals to the I

and Q inputs. The high impedance 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 at 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.

Direct Conversion Transmitter Application

■

Direct Conversion from Baseband to RF

■

High Output: –4.2dB Conversion Gain

■

High OIP3: 21.7dBm at 900MHz

■

Low Output Noise Floor at 20MHz Offset:

No RF: –159dBm/Hz

■

Low Carrier Leakage: –42dBm at 900MHz

■

High Image Rejection: –53dBc at 900MHz

■

3-Ch CDMA2000 ACPR: –70.4dBc at 900MHz

■

Integrated LO Buffer and LO Quadrature Phase

Generator

■

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

■

High Impedance DC Interface to Baseband Inputs

with 0.5V Common Mode Voltage

■

16-Lead QFN 4mm × 4mm Package

■

RFID Interrogators

■

GSM, CDMA, CDMA2000 Transmitters

■

Point-to-Point Wireless Infrastructure Tx

■

Image Reject Up-Converters for Cellular Bands

■

Low-Noise Variable Phase-Shifter for 620MHz to

1100MHz Local Oscillator Signals

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

All other trademarks are the property of their respective owners.

CDMA2000 ACPR, AltCPR and Noise vs RF

Output Power at 900MHz for 1 and 3 Carriers

VCO/SYNTHESIZER

EN

I-CH

Q-CH

BALUN

V-I

BASEBAND

GENERATOR

V-I

LT5571

5V

5571 TA01a

PA

RF = 620MHz

TO 1100MHz

I-DAC

Q-DAC

90

°

0

°

100nF

×2