A 60GHz Push-Push Voltage-Controlled Oscillator with Adaptive Gate Biasing in 28nm Bulk CMOS Technology
This paper presents a 60 GHz push-push voltage-controlled oscillator (VCO) with adaptive gate biasing realized in 28 nm bulk CMOS technology. The circuit uses a trifilar transformer — primary coil is used in the LC resonator tank, secondary coil realizes an inductive feedback of the cross-coupled pair and the third coil extracts the fundamental signal. The proposed inductive feedback technique enables an adaptive bias without use of capacitors at the gates of the cross-coupled pair transistors. The varactor banks use standard threshold voltage (VT) NMOS devices. The VCO achieves a 30% continuous frequency tuning range (FTR) and a mean phase noise (PN) of -86 dBc/Hz at 1 MHz offset from carrier. The total DC power dissipation including output buffers is less than 80 mW at a 0.9 V power supply. The circuit area excluding pads is 0.2 mm². A reference VCO without gate biasing is fabricated and used for comparison.