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. A 8-bit serial word determines the desired output gain over a 42 dB range resulting in gain changes of 6 dB/LSB.
The AD8322 comprises a digitally controlled variable attenuator of 0 dB to -42 dB, which is preceded by a low noise, fixed gain buffer and is followed by a low distortion high power amplifier. When used in a DOCSIS modem application the AD8322 works with the attenuator available on some demodulators to support the 50 dB range required by DOCSIS. The AD8322 accepts a differential or single-ended input signal. The output is specified for driving a 75 Ohm load, such as coaxial cable, although the AD8322 is capable of driving other loads.
An evaluation board is available for this product and may be ordered using the following product number AD8322-EVAL.