Design of linear CMOS VCO based on cross-coupled pair topology with double tuning technique

A low phase noise CMOS LC voltage controlled oscillator (VCO) with small VCO gain (KVCO) is presented. In order to get small KVCO and step variation across different sub-bands, we use the two sets of varactor multi-band approach to achieve low KVCO. The core power dissipation is 2.786 mW. The VCO gain of the uppermost sub-band is around 223 MHz/V and lowermost sub-band is around 184 MHz/V with 19.62% the tuning range, while the linearity is 15.2%. Under a 1.4 V supply, the VCO exhibits phase noise of −122.73 dBc/Hz at 1 MHz offset from the carrier. The Figure-of-merit (FOM) is −192.49 dBc/Hz.