A Wideband Harmonic Shaping VCO With 192-dBc/Hz Peak FoM in 65-nm CMOS

In this brief, a class- $F_{23}$ voltage-controlled oscillator (VCO) aimed at achieving low-phase noise (PN) across the tuning range without manual harmonic tuning is presented. A new head resonator (HR) based on electric coupling is proposed to expand the common-mode (CM) resonance bandwidth at 2nd harmonic ( $2f_{0}$ ) so that the 1/f noise is suppressed. The electric coupling preserves the ability to recover CM resonance bandwidth from manufacture variations. The higher differential-mode (DM) resonance frequency is positioned between $2f_{0}$ and $3f_{0}$ to mitigate Groszkowski’s frequency shift caused by the DM harmonic current. Implemented in a 65-nm CMOS process with a die area of $0.198~\text {mm}^{2}$ , the VCO exhibits a PN of −122.5 dBc/Hz at a 1-MHz offset from 8 GHz, corresponding to a peak figure of merit (FoM) of 192 dBc/Hz.