LT5518

1

5518f

■

High Input Impedance Version of the LT5528

■

Direct Conversion to 1.5GHz – 2.4GHz

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High OIP3: 22.8dBm at 2GHz

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Low Output Noise Floor at 20MHz Offset:

No RF: – 158.2dBm/Hz

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4-Ch W-CDMA ACPR: – 64dBc at 2.14GHz

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Integrated LO Buffer and LO Quadrature Phase

Generator

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

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Low Carrier Leakage: – 49dBm at 2GHz

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High Image Rejection: 40dB at 2GHz

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16-Lead QFN 4mm × 4mm Package

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Infrastructure Tx for DCS, PCS and UMTS Bands

■

Image Reject Up-Converters for DCS, PCS and UMTS

Bands

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Low Noise Variable Phase-Shifter for 1.5GHz to

2.4GHz Local Oscillator Signals

1.5GHz–2.4GHz

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 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 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 balanced I and Q

baseband input ports are intended for DC coupling from a

source with a common mode voltage level of about 2.1V.

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.

1.5GHz to 2.4GHz Direct Conversion Transmitter Application

with LO Feedthrough and Image Calibration Loop

RF OUTPUT POWER PER CARRIER (dBm)

–34

–30

–26

–22

–18

–14

–10

–65

–60

–55

5518 TA01b

–70

–75

–85

–80

–145

–140

–135

–150

–155

–165

–160

4-CH ACPR

4-CH NOISE

1-CH NOISE

4-CH ALTCPR

1-CH ALTCPR

1-CH ACPR

DOWNLINK TEST MODEL 64 DPCH

90

°

0

°

LT5518

BASEBAND

GENERATOR

CAL

LO FEEDTHROUGH

CAL OUT

IMAGE CAL OUT

PA

VCO/SYNTHESIZER

RF = 1.5GHz

TO 2.4GHz

EN

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

100nF

×2

5V

V-I

V-I

I-CHANNEL

Q-CHANNEL

BALUN

14

16

1

7

5

8, 13

11

3

5518 TA01a

I-DAC

Q-DAC

ADC

W-CDMA ACPR, AltCPR and Noise vs RF Output

Power at 2140MHz for 1 and 4 Channels

APPLICATIO S

FEATURES

DESCRIPTIO

TYPICAL APPLICATIO

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

All other trademarks are the property of their respective owners.