C-band GaAs FET power amplifiers with 70-W output power and 50% PAE for satellite communication use

This paper describes a successfully developed high-power and high-efficiency C-band GaAs FET amplifier for satellite communication systems. To realize high efficiency in a high-power amplifier, an HFET well-designed for high-power applications is developed, and precise design for an amplifier is carried out. The HFET employed achieves reduction in a gate leakage current while maintaining a high maximum drain current. For precise design of an amplifier, large-signal FET model parameters are extracted using pulsed I-V and S-parameter measurements. Based on this model, second harmonic impedances as well as fundamental impedances are determined for obtaining high efficiency and input- and output-matching circuits which are assembled in a compact package are designed to achieve a high-efficiency internally matched amplifier. As a result, the amplifier delivers a high saturated output power of 70 W and a high power-added efficiency of 51%. These characteristics are the record power performance in C-band in terms of simultaneous achievement of high power and high efficiency. A low third order intermodulation distortion of -35 dBc is also obtained at a drain voltage of 10 V.