Characterization of GaN Diodes at Microwave Frequencies using Coupled Resonator

This paper introduces a method which enables the characterization of the performances of GaN diodes directly at microwave frequencies at arbitrary input power. This is enabled by couple the GaN diodes to a microwave resonator, as a result, the input impedance of the diodes effectively detunes the resonator from its eigenmode frequency and its original loaded quality factor. In this way, some information of the diodes can be extracted from the loaded quality factor of the resonator as well as the frequency shift. To demonstrate the idea, a test circuit comprised of a single GaN diode chip with Cj0=250fF coupled to a 10 GHz microwave ring resonator is designed and simulated. It is demonstrated by ADS-CST co-simulation that the variation of the critical parameters such as Cj0 can be read out directly from the S11 of the resonator.