Monolithic 60 GHz GaAs IMPATT oscillators

A monolithic circuit design developed for GaAs IMPATT diodes to enable them to operate under CW conditions at V-band frequencies is discussed. All active and passive circuit components were fabricated on the top surface of the GaAs substrate. Good heat dissipation was achieved by distributing the device active area over a large surface area while maintaining a lumped mode of operation. More than 100-mW CW output power was obtained in the 58-65-GHz frequency range, with up to 14.5% conversion efficiency. In an alternative design, varactor diodes were integrated with the IMPATT circuits to produce the first monolithic voltage-controlled oscillators (VCOs) operating under CW conditions. A tuning bandwidth greater than 3.5 GHz was obtained at a center frequency of 70 GHz, with maximum CW output power of 40 mW