A Novel GaN/SiC MMIC Gain Switch Using a Resonant Bidirectional FET Amplifier

This paper presents a novel gain switch circuit using a resonant bidirectional field-effect transistor (FET) amplifier. The proposed switch circuit can provide insertion gain even at the millimeter-wave frequencies by using a resonant bidirectional FET amplifier. The fundamental operation of a single pole single throw (SPST) FET gain switch is successfully demonstrated as a GaN/SiC microwave monolithic integrated circuit (MMIC), which is a quite essential material to ensure the watt-class RF power handling capability for the transmission signal even at the millimeter-wave frequencies. It shows the insertion gain and isolation of 0.98 dB and 11.2 dB, respectively, at 25 GHz. Input power for 1-dB gain compression, P
1dB
, is around 6 dBm at 25 GHz. For further improvement of insertion gain and isolation, maximizing transconductance of FET and minimizing feedback capacitance by bias optimization and/or increasing stage number of a bidirectional amplifier are found to be efficient from principle analysis of the presented switch circuit. Furthermore, optimization of gate width and bias voltage improves power handling capability.