A high power C-band AlGaN/GaN HEMT MMIC VCO

A high power C-band monolithic voltage controlled oscillator (VCO) based on AlGaN/GaN HEMT is presented. The oscillator design utilizes a common-gate negative resistance structure, and a HEMT device acted as a varactor is used to control the VCO's oscillation frequency. The VCO operating at 20V drain bias and -3V gate bias exhibits an output power of 26 dBm at the center frequency of 5.96 GHz with dc-to-RF efficiency of 30%. Phase noise is estimated to be -96 dBc/Hz at 500 KHz offset. With the varactor's voltage from -1.5 V to -16 V, the frequency tuning range is from 5.61 GHz to 6.38 GHz. The measured results show high output power, good power flatness and good tuning linearity over the tuning band. This work demonstrates the potential for AlGaN/GaN HEMT technology to be used in high power microwave oscillator applications in very compact transceiver systems.