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