25.3 GHz, 4.1 mW VCO with 34.8% tuning range using a switched substrate-shield inductor

A wide tuning range CMOS VCO based on a switched substrate-shield inductor is presented. The proposed VCO uses a high quality factor, switchable inductor with smaller parasitics for frequency tuning range extension. Inductance is switched by controlling the eddy currents in a modified, floating substrate-shield. Using the proposed design, a 29 % inductance switching is achieved while maintaining a high quality factor of > 15.5. The prototype VCO shows an excellent frequency tuning range of 34.8 % and a phase noise of −120.1 dBc/Hz at 10 MHz offset for 25.3 GHz carrier frequency. This VCO has a FOMT of 192.1±2.5 dBc/Hz across the tuning range with only 4.1 mW power consumption.