Class AB CMOS Active Transformer Voltage-Controlled Oscillators

This paper presents class AB CMOS active transformers synthesized using MOS transistors only and their applications in voltage-controlled oscillators. It is shown that the class AB active transformer VCO exhibits lower phase noise than class A transformer configurations. Simulation results of self and mutual inductance, impedance, and phase noise of class A and class AB active transformer oscillators are presented. The phase noise of the designed 1.6 GHz class AB active transformer VCO in TSMC-0.18 mum 1.8 V CMOS technology is -122.9 dBc/Hz at a 1 MHz offset the carrier and is comparable to that of VCOs with passive spiral inductors.