A 12–16.3-GHz 197.7-dBc/Hz-FOMT Harmonic-Shaping VCO Using Enhanced Common-Mode Resonance Expansion Based on a Triple-Tank Coupled Resonator

This paper presents a wideband, low-phase-noise harmonic-shaping voltage-controlled oscillator (VCO) featuring a novel common-mode resonance expansion (CMRE) technique. To expand the bandwidth of conventional harmonic-shaping VCOs, a triple-tank coupled resonator (TTCR) is employed to synthesize a high-order common-mode (CM) resonance. Besides, by closely separating the poles of the TTCR, CM impedance fluctuations and deep notches are effectively mitigated across the wide frequency range. This technology significantly expands the CM high-impedance bandwidth, thereby eliminating manual tuning to align the second-harmonic resonance. Consequently, the VCO maintains a highly symmetric oscillation waveform and a near-zero DC component of the effective impulse sensitivity function (Γeff,dc), which intrinsically suppresses flicker noise up-conversion. Fabricated in a 28-nm CMOS process, the VCO occupies a core area of only 0.056 mm² and covers a tuning range of 12–16.3 GHz (30.4%). It achieves a remarkable 1/f³ phase noise corner frequency of 130 kHz at 12 GHz, maintaining below 500 kHz across the full bandwidth. The measured best phase noise is -113.3 dBc/Hz at 1-MHz offset, resulting in a peak Figure-of-Merit with tuning range (FoMT) of 197.7 dBc/Hz.