摘要
This paper presents a sub-THz oscillator based on 0.12-μm GaN HEMT technology on a 50-μm SiC substrate. Different push-push topologies are investigated for 2 nd harmonic output, and the inductive source degeneration with capacitive gate termination is proposed to realize sufficient negative resistance at the fundamental frequency. In addition, harmonic balance simulations are performed to achieve an optimum design under large signal operation. The 2 nd harmonic output is extracted at the middle of the tank inductor, and a pair of balanced 3/4 λ transmission lines are employed as RF choke to provide a clean dc supply voltage. The GaN oscillator can operate from 149 to 152.1 GHz with a frequency tuning range of 2.1 %. The peak output power is -7.3 dBm, and the phase noise (PN) is -90.7 and -120.3 dBc/Hz at the 1 and 10 MHz offset, respectively. The proposed design achieves the highest oscillation frequency using 0.12-μm GaN HEMTs, demonstrating PN and FoM among the best compared with the published mm Wave/sub-THz GaN oscillators.