21.5-to-33.4 GHz Voltage-Controlled Oscillator Using NMOS Switched Inductors in CMOS

To demonstrate the applicability of NMOS switched variable inductors in the millimeter wave frequencies, a 21.5 to 33.4 GHz wide tuning range LC voltage-controlled oscillator (LC-VCO) with frequency tunable output buffers that uses variable inductors is reported. The measured phase noise at 10 MHz offset of VCO fabricated in a 65 nm bulk CMOS process varies from -117 to -109 dBc/Hz. The oscillator core consumes 4 or 6 mA from a 1.2 V power supply. These correspond to a record 43.3% tuning range. FOMT ranges from -191.7 to -181.9 dBc/Hz. With tunable output buffers, the measured signal output power is above -15 dBm across the entire frequencies.