A Low-Noise Multi-GHz CMOS Multiloop Ring Oscillator With Coarse and Fine Frequency Tuning

A 7-GHz CMOS voltage controlled ring oscillator that employs multiloop technique for frequency boosting is presented in this paper. The circuit permits lower tuning gain through the use of coarse/fine frequency control. The lower tuning gain also translates into a lower sensitivity to the voltage at the control lines. Fabricated in a standard 0.13-mum CMOS process, the proposed voltage-controlled ring oscillator exhibits a low phase noise of -103.4 dBc/Hz at 1 MHz offset from the center frequency of 7.64 GHz, while consuming a current of 40 mA excluding the buffer.