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LTC6412 - 800MHz, 31dB Range Analog-Controlled VGA

The LTC6412 is a fully differential variable gain amplifier with linear-in-dB analog gain control. It is designed for AC-coupled operation in IF receiver chains from 1MHz to 500MHz. The part has a constant OIP3 across a wide output amplitude range and across the 31dB gain control range. The output noise (NF + Gain) is also fl at versus gain to provide a uniform spurious-free dynamic range (SFDR) >120dB over the full gain control range at 240MHz.

The LTC6412 is ideal for interfacing with the LT®5527 and LT5557 downconverting mixers, LTC6410-6 IF amplifier and the LTC6400/LTC6401/LTC6416 ADC drivers for use in 12-, 14-, and 16-bit ADC applications.

The LTC6412 recovers quickly from an overdrive condition, and the EN pin allows for a fast output signal disable to protect sensitive downstream components. Asserting the SHDN pin reduces the current consumption below 1mA for power-down or sleep modes.

Features 800MHz –3dB Small-Signal Bandwidth Continuously-Adjustable Gain Control –14dB to +17dB Linear-in-dB Gain Range 35dBm OIP3 at 240MHz Across All Gain Settings 10dB Noise Figure at Maximum Gain (IIP3 – NF) = +8dBm at 240MHz Across All Gains 2.7nV/√Hz Input Referred Noise Differential Inputs and Outputs 50Ω Input Impedance Across all Gains Single Supply Operation from 3V to 3.6V 110mA Supply Current 4mm × 4mm × 0.75mm 24-Pin QFN Package Typical Application

Applications IF Signal Chain Automatic Gain Control (AGC) 2.5G and 3G Cellular Basestation Transceivers WiMAX, WiBro, WLAN Receivers Satellite and GPS Receiver IF Packaging

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