LT5575

1

5575f

LO INPUT POWER (dBm)

–15

15

20

25

5

5575 TA01b

10

5

0

–10

–5

0

35

30

30

40

50

20

10

0

70

60

CONV

GAIN

DSB NF

IIP2

IIP3

–40

°C

25

°C

85

°C

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

800MHz to 2.7GHz

High Linearity Direct Conversion

Quadrature Demodulator

quadrature demodulator optimized for high linearity

receiver applications. It is suitable for communications

receivers where an RF signal is directly converted into I

and Q baseband signals with bandwidth up to 490MHz.

The LT5575 incorporates balanced I and Q mixers, LO

buffer amplifiers and a precision, high frequency quadrature

phase shifter. The integrated on-chip broadband transform-

ers provide 50Ω single-ended interfaces at the RF and LO

inputs. Only a few external capacitors are needed for its

application in an RF receiver system.

The high linearity of the LT5575 provides excellent spur-

free dynamic range for the receiver. This direct conversion

demodulator can eliminate the need for intermediate fre-

quency (IF) signal processing, as well as the corresponding

requirements for image filtering and IF filtering. Channel

filtering can be performed directly at the outputs of the I

and Q channels. These outputs can interface directly to

channel-select filters (LPFs) or to baseband amplifiers.

High Signal-Level I/Q Demodulator for Wireless Infrastructure

■

Input Frequency Range: 0.8GHz to 2.7GHz*

■

50Ω Single-Ended RF and LO Ports

■

High IIP3: 28dBm at 900MHz, 22.6dBm at 1.9GHz

■

High IIP2: 54.1dBm at 900MHz, 60dBm at 1.9GHz

■

Input P1dB: 13.2dBm at 900MHz

■

I/Q Gain Mismatch: 0.04dB Typical

■

I/Q Phase Mismatch: 0.4° Typical

■

Low Output DC Offsets

■

Noise Figure: 12.8dB at 900MHz, 12.7dB at 1.9GHz

■

Conversion Gain: 3dB at 900MHz, 4.2dB at 1.9GHz

■

Very Few External Components

■

Shutdown Mode

■

16-Lead QFN 4mm × 4mm Package with

Exposed Pad

■

Cellular/PCS/UMTS Infrastructure

■

RFID Reader

■

High Linearity Direct Conversion I/Q Receiver

Conversion Gain, NF, IIP3 and IIP2

vs LO Input Power at 1900MHz

BPF

+5V

BPF

RF

INPUT

RF

LPF

LT5575

+

–

0

°

LO

LO INPUT

EN

ENABLE

LPF

+

–

90

°

0

°/90°

5575 TA01

LNA

VGA

VGA

A/D

A/D

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

All other trademarks are the property of their respective owners.

*Operation over a wider frequency range is possible with reduced performance. Consult

the factory.