LT5558 데이터 시트보기 (PDF) - Linear Technology

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LT5558

600MHz to 1100MHz High Linearity Direct Quadrature Modulator

Linear Technology 

FEATURES

■ Direct Conversion from Baseband to RF

■ High OIP3: + 22.4dBm at 900MHz

■ Low Output Noise Floor at 20MHz Offset:

No RF: –158dBm/Hz

POUT = 4dBm: –152.7dBm/Hz

■ Low Carrier Leakage: –43.7dBm at 900MHz

■ High Image Rejection: –49dBc at 900MHz

■ 3 Channel 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 Interface to Baseband Inputs

with 2.1V Common Mode Voltage

■ 16-Lead QFN 4mm × 4mm Package

APPLICATIONS

■ RFID Single-Sideband Transmitters

■ Infrastructure TX for Cellular and ISM Bands

■ Image Reject Up-Converters for Cellular Bands

■ Low-Noise Variable Phase-Shifter for 600MHz to

1100MHz Local Oscillator Signals

■ Microwave Links

LT5558

600MHz to 1100MHz

High Linearity Direct

Quadrature Modulator

DESCRIPTION

The LT®5558 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

GSM, EDGE, CDMA, CDMA2000, 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 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 which produce the LO drive for the mixers.

The supply voltage range is 4.5V to 5.25V.

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

All other trademarks are the property of their respective owners.

TYPICAL APPLICATION

600MHz to 1100MHz Direct Conversion Transmitter Application

∫ IDAC

EN

∫ QDAC

VCC

8, 13

5V

2 x 100nF

14

16

V-1

I-CH

1

O°

LT5558

RF = 600MHz TO

1100MHz

11 PA

90°

7

Q-CH

5

V-1

BALUN

BASEBAND

GENERATOR

2, 4, 6, 9, 10,

12, 15, 17

3

VCO/SYNTHESIZER

5558 TA01

CDMA2000 ACPR, AltCPR and Noise vs

RF Output Power at 900MHz for 1 and 3 Carriers

–40

DOWNLINK TEST

MODEL 64 DPCH

–50

3-CH ACPR

3-CH ALTCPR

–60

–70

–110

–120

–130

1-CH ACPR

–140

–80

1-CH ALTCPR

1-CH NOISE

–150

3-CH NOISE

–90

–30 –25 –20 –15 –10 –5

–160

0

RF OUTPUT POWER PER CARRIER (dBm)

5558 TA01b

5558fa

1

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