A novel CMOS low-phase-noise VCO with enlarged tuning range

A low phase noise, large tuning range VCO is implemented using 0.25 um CMOS process. The new method, which can enlarge the tuning range and improve phase noise of CMOS VCO, is presented in this paper. It combines the dominant parallel resonance using standard passive on-chip spiral inductors and the additional series resonance using active inductors consisted of MOSFET, resistor and capacitor. Without others parameters variation, the general VCO can form the proposed VCO by adding two resistors and two capacitors; and the proposed VCO has the same power consumption as the general VCO, which is 10 mW in this design. As for the performance, the tuning range of the proposed VCO is improved 6% and the achieved highest frequency is improved about 13%. Also, it is the most important that the phase noise is improved up to 15 dB at most.