A 1.6–10.9 GHz voltage-controlled ring oscillator for the serial interface of high-speed data converters

A wideband ring voltage controlled oscillator (VCO) for the serial interface circuits in high-resolution data converters with wide clock frequency range is presented in this paper. The active loads of the proposed differential delay cell in the VCO is realized by a pair of PMOS current source in parallel with a pair of adjustable cross-coupled PMOS transistors, which are controlled simultaneously by the control terminal to enlarge the tuning range of the VCO. In order to achieve a maximum oscillation frequency of over 10GHz, only three stages of differential delay cells are adopted in the VCO. The VCO is designed in a 0.18µm CMOS technology. Simulated results show that the VCO achieves an oscillation frequency range of 1.6GHz to 10.9 GHz, and a phase noise of −92.25dBc/Hz@1MHz when the center frequency is 1.561 GHz. The VCO consumes 19.1 mW from a 1.8 V supply.