W-Band GaN HEMT Switch Using the State-Dependent Concurrent Matching Method

Abstract

In this study, a W-band GaN single-pole single-throw (SPST) switch was designed. To realize the pass and isolation modes of the SPST switch, we proposed the design technique of a unit branch consisting of one transistor and one transmission. The characteristic impedance and length of the transmission line were determined by the impedance and the angle at which the straight line connecting the impedances of the on and off states of the transistor meets the real axis of the Smith chart. Using the design technique, the matching networks for the pass and isolation modes of the switch are concurrently completed. In order to improve the insertion loss and isolation characteristics of the switch, the size of the transistor and the number of unit branches were investigated. To verify the feasibility of the proposed design technique, we designed the W-band SPST switch using a 100 nm GaN HEMT process. The measured insertion loss and isolation were below 2.9 dB and above 23.5 dB, respectively, in the frequency range from 91 GHz to 101 GHz.