Abstract
A 9 GHz low phase noise class-C voltage controlled oscillator (VCOs) with an 8-shaped transformer configuration using 0.18-μm CMOS technology is presented. By utilizing the 8-shaped transformer, the proposed class-C VCO can be operated at reduced dc power consumption while maintaining circuit performance in terms of phase noise and limiting EMC (Electro-Magnetic Compatibility) issues when the symmetrical structures are considered. Consuming a dc current of 5.5 mA with the supply voltage of 1.8 V, the class-C VCO exhibits a frequency tuning range of 1.4 GHz, a phase noise of -117.4 dBc/Hz at 1 MHz offset frequency away from the 8.94 GHz carrier, and a figure of merit up to 186.4 dBc/Hz.