Floating active inductor based Class-C VCO with 8 digitally tuned sub-bands

A fully integrated floating active inductor based voltage-controlled oscillator (VCO) is presented. The active inductor employs voltage differencing transconductance amplifier (VDTA) asa building block. The designed VCO achieves frequency tuning by varying the bias current through the VDTA and utilizes a Class-C topology for improving the phase noise performance. The inductor-less VCO is designed and implemented in a 45-nm CMOS process and its performance is estimated using Virtuoso ADE of Cadence. Operating at a supply voltage of ±1V, the proposed VCO consumes 0.44–1.1mW corresponding to the oscillation frequency of 1.1–1.8GHz thereby exhibiting a tuning range of 48.27%. The phase noise of the VCO lies in the range of −94.12 to −98.37 dBc/Hz at 1MHz offset resulting in a FOM of −172.14 to −176.69 dBc/Hz.