GaN/SiC SPDT gain switch MMICs utilizing bidirectional FET amplifiers for millimeter-wave applications

Abstract GaN/SiC single pole double throw gain switch microwave monolithic integrated circuits (MMICs) utilizing bidirectional field-effect transistor (FET) amplifiers have been successfully demonstrated in both resonant and non-resonant circuit configurations for millimeter-wave applications. The resonant-type bidirectional FET amplifier has anti-parallel FET amplifier pair and a parallel inductor, where LC parallel resonance with cold pinched-off state FET is employed for signal direction determination and loop blocking. On the other hand, the non-resonant-type bidirectional amplifier has either gate-to-gate facing or drain-to-drain facing circuit configurations where one FET is in a cold pinched-off state FET for matching network circuit component, and another one is biased for amplifiers to obtain gain characteristics. The designed MMICs has been fabricated by GaN/SiC Foundry process. The peak gain and isolation of the resonant-type are 2.64 dB and 10.8 dB at 24.25 GHz, respectively, while the non-resonant-type achieves 5.07 dB gain and 6.35 dB isolation at 28.5 GHz.