A Multi-Stage 4-Watt Amplifier with GaAs FET'S For a 5 GHZ Microwave Equipment

Power amplifiers for microwave equipment for both analog and digital signal transmission can be realized with GaAs field effect transistors up to frequencies of approx. 15 GHz. More specifically, with commercially available devices which are derated to allow for high ambient temperatures, it is possible to achieve an output power of 3 to 4 watts up to approx. 8 GHz and of 1 to 2 w for frequencies above 8 G Hz. The amplifier presented here is designed to have a typical output power of 4w at the 1 dB compression point over the frequency range of 4.4 to 5 GHz. The subjects of discussion are the influence of temperature on the output power, the large-signal S-parameter measurements and the effects of transistor parameter variations on the circuit design. This is followed by a description of the realized circuits, as well as a listing of the most significant amplifier characteristics.