5 V CATV Line Driver Fine Step Output Power Control

The AD8325 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 59.45 dB range resulting in gain changes of 0.7526 dB/LSB.

The AD8325 is packaged in a low-cost 28-lead TSSOP, operates from a single 5 V supply, and has an operational temperature range of -40°C to +85°C.

An evaluation board is available for this product and may be ordered using the following product number AD8325-EVAL.

* Supports DOCSIS Standard for Reverse Path Transmission

* Gain Programmable in 0.75 dB Steps Over a 59.45 dB Range

* Low Distortion at 61 dBmV Output

–57 dBc SFDR at 21 MHz

–55 dBc SFDR at 42 MHz

* Output Noise Level: –48 dBmV in 160 kHz

* Maintains 75Ω Output Impedance

*

Transmit Enable and Transmit Disable Modes

* Upper Bandwidth:100 MHz (Full Gain Range)

* 5 V Supply Operation

* Supports SPI Interfaces