GaAs field effect transistors for power amplifiers and oscillators in microwave systems

Two aspects were pursued simultaneously: the development of ion implanted GaAs power MESFETs and the development of modules with FETs purchased on the market, i.e. with FETs on epitaxially grown active layers. The basic cell of the FET with the gate dimensions L X W = 1 micrometer X 1500 micrometer on ion implanted layers has an output power of 27.2 dBm at 6 dB gain, 20% power added efficiency, and a saturated power of 640 mW at 6 GHz. The same cell on epi-layers gives almost identical results: 26 dBm at 6 dB gain, 25% efficiency, 680 mW saturated power. Two ion implanted cells connected in parallel produce 1.1 W saturated power. A three stage FET amplifier with open-ended stubs for matching has 18 dB gain in the linear region and a saturated output power of 2.5 W at 6.4 to 7.1 GHz. A two-stage amplifier with bandpass filter matching, which consisted of adjustable elements for tuning, has 18 dB gain and a saturated output power of almost 1 W at 3.9 to 4.1 GHz. A FET oscillator with cavity resonator produces 30 to 80 mW of power at 16.5 GHz with 15% and 12% efficiency, respectively.