GENERAL DESCRIPTION

The AD8322 is a low-cost, digitally controlled variable gain amplifier optimized for coaxial line driving applications such as cable modems that are designed to the MCNS-DOCSIS upstream standard. An 8-bit serial word determines the desired output gain over a 42.14 dB range, with gain steps of 6.02 dB/major carry.

FEATURES

Supports DOCSIS Standard for Reverse Path

Transmission

Gain Programmable in 6 dB Steps Over a 42 dB

Range

Low Distortion at 60 dBmV Output

–58 dBc SFDR at 21 MHz

–56 dBc SFDR at 42 MHz

Output Noise Level

–46 dBmV in 160 kHz Bandwidth

Maintains 75 Ω Output Impedance

Power-Up and Power-Down Condition

180 MHz Bandwidth

5 V Supply Operation

Supports SPI Interfaces

APPLICATIONS

Gain Programmable Line Driver

DOCSIS-Compliant Data Modems

Interactive Set-Top Boxes

PC Plug-in Modems

General-Purpose Digitally Controlled Variable Gain Block