A VCO With Robust Implicit Common-Mode Resonance Against Nonideal Decoupling Network

This letter describes a voltage-controlled oscillator (VCO) that can achieve robust flicker noise suppression when the decoupling network is not ideal. Utilizing a multitap transformer, the implicit common-mode (CM) impedance quality factor (Q factor) degradation from the parasitic resistance of the decoupling network can be avoided. Fabricated in 65-nm CMOS, the proposed VCO realizes a flicker corner (1/f3 corner) from 70 to 230 kHz across the tuning range from 4.24 to 4.80 GHz. The proposed VCO achieves a phase noise (PN) of -127.4 dBc/Hz at 1 MHz offset frequency fofst and a Figure of Merit (FoM) of 193.1 dB. The core area of the VCO is 0.29 mm2.