Subharmonic Injection-locked PMOS Load VCO for Ultra-low Phase Noise and Extended Tuning Range

This paper presents a voltage-controlled oscillator (VCO) architecture that integrates a subharmonic injection locking mechanism to significantly enhance its phase noise (PN) performance and figure of merit (FoM). The proposed VCO utilizes a split-load PMOS ring oscillator as the master oscillator and a negative-gm LC cross-coupled oscillator as the slave. The output of the slave oscillator is injected into the master oscillator, leveraging the injection locking phenomenon to synchronize their frequencies and phases. This synchronization significantly reduces the phase noise of the master oscillator, achieving a noise performance of $131.49 \mathrm{dBc} / \mathrm{Hz}$, compared to a figure of $-55.79 \mathrm{dBc} / \mathrm{Hz}$ for the standalone ring oscillator. Operating at a frequency of 27.8 GHz with a supply voltage of 2 V, the oscillator demonstrates a tuning range from 6.06 GHz to 28.49 GHz, representing a tuning of $130 \%$ while maintaining a low power consumption of 1.5 mW. This architecture offers potential for high-performance applications in RF communication, millimeter-wave systems, and radar technology.