New low power differential VCO circuit designs with active load and IMOS varactor

In this paper, low power differential voltage-controlled oscillators (VCOs) have been reported utilizing the active load and inversion mode MOSFET (IMOS) varactor in the delay stages. VCO circuits operation is based on two NOR gates in differential mode, variations in gate control voltage of the NMOS/PMOS active load, and the varactor control voltage of IMOS. For VCO based on NMOS active load, variations in gate control voltage from 1.0 V to 2.0 V exhibit frequency variations from 6.687 GHz to 6.395 GHz. For VCO based on PMOS active load, variations in gate control voltage of PMOS active load from −0.5 V to 0.5 V provide frequency variations from 5.726 GHz to 6.142 GHz. For VCO based on IMOS varactor, variations in varactor control voltage of IMOS from 1.0 V to 2.0 V shows variations in output frequency from 3.796 GHz to 4.499 GHz with power dissipation of 2.06 mW. Proposed VCOs shows a phase noise of −76.20 dBc/Hz@1MHz for NMOS active load, −73.42 dBc/Hz@1MHz for PMOS active load and −75.63 dBc/Hz@1MHz for IMOS varactor load and the figure of merit (FoM) for the VCOs are −149.43 dBc/Hz, −145.58 dBc/Hz and −145.17 dBc/Hz, respectively.