Design and Characterization of a GaAs FET Power Amplifiers for a 64 QAM Digital Radio Transmitter

This paper describes the design of the model 328A, a solid 6 GHz GaAs FET power amplifier (SSPA), which is used in the AT&T DR6-30-135 digital radio system. The radio employs at 64 QAM format which places severe restrictions on the overall system linearity, particularly in the transmitter. 

We first present a general description of the transmitter and overall SSPA, and the overall transmitter with and without IF predistortion. Finally, results are presented concerning the digital radio system performance and field experience obtained with this design.