FET Power Amplifier

This program had as its objective the development of an X-band GaAs FET power amplifier. Advances were made in materials, device, and microwave circuit technology during the course of the amplifier development. Devices with 2400 micrometer gate width from nine device runs seven different epitaxial slices produced 1 W or more at 9 GHz with 4 dB gain and power-added efficiencies of 20 to 30. Two device chips were connected in parallel to give a total gate width of 4800 micrometer. In this case, an output power of 2.5 W was achieved at 8 GHz with 4.0 dB gain and 25 power-added efficiency. An output power cw of 360 mW was achieved with a gain of 20.5 dB at 9.3 GHz for a three- stage FET amplifier. The 3 dB bandwidth was 1.0 GHz 8.9 to 9.9 GHz. This performance exceeded the contract goals. A microstrip hybrid FET three-stage IMPATT amplifier was fabricated that had an output power of 1.2 W with 26 dB gain at 9.5 GHz with a 700 MHz 3 dB bandwidth. This amplifier also met the performance goals. Two three-stage FET amplifiers and two FETIMPATT hybrid amplifiers were delivered to AFAL.