LT5517

1

5517f

BPF

5V

BPF

LPF

LT5517

+

–

0

°

2xLO

EN

ENABLE

2xLO

INPUT

LPF

DSP

+

–

90

°

÷2

5517 F01

LNA

VGA

VGA

s

Wireless Infrastructure

s

High Linearity Direct Conversion I/Q Receiver

s

High Linearity I/Q Demodulator

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

s

RF Input Frequency Range: 40MHz to 900MHz

s

High IIP3: 21dBm at 800MHz

s

High IIP2: 58dBm at 800MHz

s

I/Q Gain Mismatch: 0.3dB Max

s

I/Q Phase Mismatch: 0.7

°

s

Noise Figure: 12.4dB at 800MHz

s

Conversion Gain: 3.3dB at 800MHz

s

Baseband Bandwidth: 130MHz

s

Single Ended, 50

Ω Matched 2XLO Input

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Shutdown Mode

s

16-Lead QFN (4mm

× 4mm) Package

with Exposed Pad

40MHz to 900MHz

Quadrature Demodulator

Figure 1. High Signal-Level I/Q Demodulator for 450MHz Infrastructure Receiver

I/Q Output Power, IM3, IM2

vs RF Input Power

The LT

lator optimized for high linearity receiver applications

where high dynamic range is important. It is suitable for

communications receivers where an RF or IF signal is

directly converted into I and Q baseband signals with a

bandwidth up to 130MHz. The LT5517 incorporates bal-

anced I and Q mixers, LO buffer amplifiers and a precision,

broadband quadrature generator derived from an on-chip

divide-by-two circuit.

The superior linearity and low noise performance of the

LT5517 is achieved across its full frequency range. A well-

balanced divide-by-two circuit generates precision quadra-

ture LO carriers to drive the I mixer and the Q mixer.

Consequently, the outputs of the I-channel and the

Q-channel are well matched in amplitude, and their phases

are 90

° apart. The LT5517 also provides excellent 50Ω

impedance matching at the 2XLO port across its entire

frequency range.

RF INPUT POWER (dBm)

–18

–100

–80

–60

–40

–20

0

20

IM3

IM2

–14

–10

–6

–2

5517 F01b

2

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO