The AD8326 is a high-output power, digitally controlled, variable gain amplifier optimized for coaxial line driving applications such as data and telephony cable modems that are designed to the MCNS-DOCSIS upstream standard. An 8-bit serial word determines the desired output gain over a 53.5 dB range resulting in gain changes of 0.75 dB/LSB. The AD8326 is offered in two models, each optimized to support the desired output power and resulting performance. The AD8326 comprises a digitally controlled variable attenuator of 0 dB to –54 dB, that is preceded by a low noise, fixed-gain buffer and is followed by a low distortion high-power amplifier. The AD8326 accepts a differential or single-ended input signal. The output is designed to drive a 75 Ω load, such as coaxial cable, although the AD8326 is capable of driving other loads. When driving 67 dBm into a 75 Ω load, the AD8326ARP provides a worst harmonic of only –59 dBc at 21 MHz and –57 dBc at 42 MHz. When driving 65 dBmV into a 75 Ω load, the AD8326ARE provides a worst harmonic of only –62 dBc at 21 MHz and –60 dBc at 42 MHz.