A 300-GHz high-power high-efficiency voltage-controlled oscillator with low power variation

This letter presents a 300-GHz voltage-controlled oscillator (VCO) with high output power and efficiency. The VCO core employs a differential Colpitts topology with inductive degeneration to facilitate a fundamental oscillation at 300 GHz. A common-base output buffer regulates the output power to minimize the power variation during the frequency tuning. The 300-GHz VCO is fabricated in a 130-nm InP double heterojunction bipolar transistor (DHBT) technology. The VCO exhibits a measured frequency tuning range of 9.9 GHz (294.9-304.8 GHz). The peak output power is measured to be 4.7 dBm at 297 GHz. The dc power consumption is 75.6 mW, leading to a high dc-to-RF conversion efficiency of 3.9%. The VCO output power is maintained nearly constant with only a 0.3-dB variation over the entire frequency tuning range. The phase noise is -86.6 dBc/Hz at 10-MHz offset frequency.