11-GHz CMOS differential VCO with back-gate transformer feedback

A fully integrated back-gate transformer feedback CMOS differential voltage-controlled oscillator (VCO) has been designed for high-frequency and low-phase noise operation using an 0.18-μm CMOS process. The proposed VCO topology utilizes the monolithic transformer feedback configuration from the drain to the back-gate of the switching transistors in VCO. The VCO operating in an 11-GHz band shows the phase noise of -109dBc/Hz at 1-MHz offset, and draws around 3.8mA in the differential core circuits from a 1.8-V power supply.