Some design aspects on 5GHz CMOS quadrature VCO with fully integrated LC-tank

Firstly, a prototype circuit of 5GHz fully integrated CMOS quadrature voltage controlled oscillator (QVCO) realized in TSMC 0.18μm CMOS technology. The QVCO could be tuned between 5.75 GHz and 5.95 GHz, and shows a phase noise of -105dBc/Hz at 5MHz offset frequency from the carrier by testing the one-side of the differential outputs, for a current consumption of 10mA from a 1.8V power supply. Then, some design aspects on QVCO are analyzed focusing on the optimization of phase noise. According to the optimizing methods of phase noise, QVCO is classified into two types. At last, a design guide is proposed and a new QVCO architecture is predicted that has better phase noise in QVCO in future.