A Highly Efficient UHF Power Amplifier Using GaAs FETs for Space Applications

This paper discusses a highly efficient linear GaAs MESFET UHF power amplifier developed for application in an SSPA for a government space program. GaAs devices have not been used at UHF because of concerns over stability and their high cost relative to other available device technology. In space, efficiency is a primary concern and reliability can outweigh piece part costs. This amplifier typically produces a power added efficiency of greater than 70 percent and the excellent linearity needed for one of the first applications of WCDMA in space communications. This paper begins by describing the overall UHF subsystem and SSPA, and then presents details of the power amplifier design technique along with measured test results.