Low phase noise CMOS voltage-controlled oscillators

Design considerations and performance comparisons for several low phase noise CMOS voltage-controlled oscillator (VCO) topologies are presented including the Hartley, quadrature Colpitts, Clapp, and tuned-input tuned-output configurations. An indirect approach for high-frequency signal generation using a VCO coupled with a 2X passive frequency multiplier is also described. Several of the structures are attractive alternatives to the conventional LC tank VCO.