DESCRIPTION

The AD8321 is a low cost digitally controlled variable gain amplifier optimized for coaxial line driving applications such as cable modems that are designed to the DOCSIS* (upstream) standard. An 8-bit serial word determines the desired output gain over a 53.4 dB range, resulting in gain changes of 0.75 dB/LSB.

FEATURES

Linear in dB Gain Response Over >53 dB Range

Drives Low Distortion >11 dBm Signal into 75 Ω Load:

–53 dBc SFDR at 42 MHz

Very Low Output Noise Level

Maintains Constant 75 Ω Output Impedance

Power-Up and Power-Down Condition

No Line Transformer Required

Upper Bandwidth: 235 MHz (Min Gain)

9 V Single Supply Operation

Power-Down Functionality

Supports SPI Interface

Low Cost

APPLICATIONS

Gain Programmable Line Driver

HFC High Speed Data Modems

Interactive CATV Set-Top Boxes

CATV Plant Test Equipment

General Purpose IF Variable Gain Block