LT5528

1

5528f

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 up-converting 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.

■

Direct Conversion to 1.5GHz to 2.4GHz

■

High OIP3: 21.8dBm at 2GHz

■

Low Output Noise Floor at 5MHz Offset:

No RF: –159.3dBm/Hz

■

4-Ch W-CDMA ACPR: –66dBc at 2.14GHz

■

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: –42dBm at 2GHz

■

High Image Rejection: 45dB at 2GHz

■

16-Lead QFN 4mm × 4mm Package

1.5GHz to 2.4GHz Direct Conversion Transmitter Application

with LO Feed-Through and Image Calibration Loop

90°

0°

LT5528

BASEBAND

DSP

CAL

LO FEED-THROUGH CAL OUT

IMAGE CAL OUT

PA

VCO/SYNTHESIZER

RF = 1.5GHz

TO 2.4GHz

EN

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

5V

V-I

V-I

I-CHANNEL

Q-CHANNEL

BALUN

14

16

1

7

5

8, 13

11

3

5528 TA01a

I-DAC

Q-DAC

ADC

1.5GHz to 2.4GHz

High Linearity Direct

Quadrature Modulator

■

Infrastructure Tx for DCS, PCS and UMTS Bands

■

Image Reject Up-Converters for PCS and UMTS

Bands

■

Low-Noise Variable Phase-Shifter for 1.5GHz to

2.4GHz Local Oscillator Signals

RF OUTPUT POWER PER CARRIER (dBm)

–38

–42

–55

–60

–65

–70

–75

–80

–140

–150

–145

–155

–165

–160

5528 TA01b

–14

–18

–22

–26

–30

–34

4-CH ACPR

2-CH ACPR

1-CH ACPR

4-CH AltCPR

2-CH AltCPR

DOWNLINK TEST MODEL 64 DPCH

1-CH AltCPR

4-CH NOISE

1-CH NOISE

W-CDMA ACPR, AltCPR and Noise vs RF Output

Power at 2140MHz for 1, 2 and 4 Channels

APPLICATIO S

FEATURES

DESCRIPTIO

TYPICAL APPLICATIO

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