A wide frequency range and adjustable duty cycle CMOS ring voltage controlled oscillator

This paper presents a voltage controlled ring oscillator (VCO) with wide tuning range and adjustable duty cycle. The circuit was designed using Rohm 0.18μm technology with 1.5V supply voltage. The simulation results show that the VCO oscillates from 300Hz up to 1.4GHz, while the duty cycle can be adjusted 20-80% independently from the oscillating frequency.