Fine frequency tuning using injection-control in a 1.2V 65nm CMOS quadrature oscillator

Fine frequency tuning based on injection locking applicable to analog and digitally-controlled LC quadrature-oscillators is proposed. The operating frequency varies linearly with relative strength of the controllable injected signal with a slope proportional to 1/2Q. Its linear characteristic makes it suitable for digitization. An 8 GHz prototype fabricated in 65nm CMOS, operating from a 1.2 V supply, exhibits linear fine-tuning of 60 MHz at an output swing where digital switches and CMOS varactors would encounter fine-tuning limitations. For 10 mA drawn by differential oscillator cores, the phase noise at 1 MHz, varies by only 1.15 dB, and quadrature error from 0.3-1.6 degrees over the fine-tuning range. The deviation of the fine-tuning from a linear response is less than 4%.