Design of Ultra-Low Phase Noise and High Power Integrated Oscillator in $0.25~\mu{\rm m}$ GaN-on-SiC HEMT Technology

A novel ultra-low phase noise and high power integrated oscillator is presented in this letter. The proposed oscillator, based on GaN-on-SiC high electron mobility transistor (HEMT) with 0.25 μm gate length and 800 μm gate width, delivers 21 dBm output power when biased at V_GS=-3 V and V_DD = 28 V. Phase noise was measured to be -112 dBc/Hz at 100 kHz offset and -135 dBc/Hz at 1 MHz offset from 7.9 GHz carrier, respectively. To the best of our knowledge, it achieves the lowest phase noise compared to other GaN HEMT based integrated oscillators. It is also comparable in performance to the state-of-the-art ultra-low phase noise oscillators designed in InGaP technology, while delivering more than 10 times higher output power. In addition, this oscillator also exhibits a minimum second harmonic suppression of 28.65 dBc and more than 60 dBc third harmonic suppression. The chip size is 1.1×0.6 mm². The results show that the proposed oscillator has the potential to be used for both low phase noise and high power microwave source applications.