A 0.07 mm $^{2}$ 2.2 mW 10 GHz Current-Reuse Class-B/C Hybrid VCO Achieving 196-dBc/Hz FoM $_{{\rm A}}$

This Letter describes a current-reuse class-B/C hybrid voltage-controlled oscillator (VCO) with robust startup, enhanced phase noise and differential balancing at small area and power. Specifically, an asymmetrical CMOS class-C core is aided by a symmetrical NMOS-only class-B core that effectively shares the bias current for deeper class-C operation of the former; wider margin of startup against PVT variations, and lower amplitude imbalance against oscillation frequencies. Moreover, this topology adds the freedom of adjustable peak dynamic current and boosts the oscillation swing at low power. The spiral inductors with patterned ground shields shrink the die size. Fabricated in 65 nm CMOS, the 0.07 mm ² VCO prototype exhibits 10.15-to-11.17 GHz tunability, and -107.73-dBc/Hz phase noise at 1 MHz offset, while dissipating merely 2.2 mW at 1.2 V. The achieved area-included figure-of-merit (FoM A = 196 dBc/Hz) favorably compares with the state-of-the-art.