A Noise-Shifting Differential Colpitts VCO

Abstract—A novel noise-shifting differential Colpitts VCO is presented. It uses current switching to lower phase noise by cy-clostationary noise alignment and improve the start-up condition. A design strategy is also devised to enhance the phase noise per-formance of quadrature coupled oscillators. Two integrated VCOs are presented as design examples. Index Terms—Analog integrated circuits, CMOS integrated cir-cuits, LC oscillators, optimization, phase noise, quadrature oscil-lators, radio frequency, voltage-controlled oscillators. I