Voltage Controlled Ring Oscillator for Low Phase Noise Application

Abstract

A design for a voltage-controlled ring oscillator (VCO) is presented. The design allows an implementation of low frequency ring oscillator using relatively small devices and less stage. It is implemented using .18um technology provided by TSMC technology using 3.3V power supply. The VCO topology exhibits a very wide tuning range from few Hz to 368.9 MHz. It also features the rapid voltage swing and the 48% duty cycle with good transient characteristics which is difficult to get from the conventional oscillator. Its power dissipation at the maximum oscillation frequency is 35.05 mW. A frame work for modeling the phase noise in complementary metal-oxide-semiconductor (CMOS) ring oscillators. Phase noise for simulated circuit is -88dbc when offset frequency is 10 5 HZ.