A 4.5-to-13.5-GHz Single-Transformer Quad-Mode VCO With 202.5-dBc/Hz FoMT

This letter reports a single-transformer quad-mode voltage-controlled oscillator (VCO) in 28-nm CMOS. Specially, our quad-mode VCO integrates the mode-switching, core-switching, and inductor-switching approaches in a single-transformer-based resonator for frequency tuning range (FTR) extension. Thus, the wideband oscillator could mitigate the tradeoff between the phase noise (PN) and octave FTR while preserving the silicon area efficiency. The proposed quad-mode VCO scores a PN of −136.6 dBc/Hz with a superior peak FoMT of 202.5 dBc/Hz at a 10-MHz offset over a 100% FTR (4.5–13.5 GHz). The VCO occupies a core area of 0.12 mm2 and dissipates 4.5–11.5 mW across the FTR.