Ring oscillator using current mirror inverter stages

Abstract

A ring oscillator having an odd number of single ended stages, each stage including two transistors connected as a current mirror. The stage provides for low-voltage performance and improved process tolerance characteristics.

Description

FIELD OF THE INVENTIONThis invention relates to an oscillator and more particularly to a ring oscillator.BACKGROUND OF THE INVENTIONNew manufacturing processes and new applications are forcing power supplies to lower voltages (3.3 v now, with 2.4 v and 1.5 v being expected soon). Advanced Phase-Locked Loops require stable oscillators which may be varied in frequency by a control signal.To help achieve frequency stability, oscillators integrated into a noisy VLSI environment often use a regulator to generate a quiet power supply. This usually has to be at an even lower voltage than the normal power supply.There is thus a desire to provide oscillators which can work at these very low supply voltages and still produce high quality, high frequency output signals.Reference is made to IBM Technical Disclosure Bulletin, Vol. 31, No. 2, July 1988, pages 154 to 156 "CMOS Ring Oscillator with controlled frequency" which describes a ring oscillator using CMOS transistors and is designed to giv...

AI Technical Summary

Benefits of technology

The first and second transistors can be n-channel field effect devices having a gate as the control node and the source-drain path as the controllable path. As the transistors are of the same type, process variations affect the transistors in the same manner. The maximum frequency of operation is limited only by the ratio of gain to gate capacitance.

Problems solved by technology

The maximum value of m is limited by practical considerations and particularly layout considerations.

Images