Quadrature Oscillator Design with G_m-C Structure

Abstract

This paper presents an attractive and new quadrature oscillator based on Gm-C structure. The proposed quadrature oscillator is achieved with MOS transistors and two capacitors. The passive capacitors are grounded, which is an advantage for integrated circuit implementation. The theoretical results are verified by LTSPICE simulation using the 0.18 µm CMOS technology from TSMC. The proposed quadrature oscillator circuit can be used in several communication and instrumentation systems. Circuit realizations of the quadrature oscillators, given in [1], require some floating capacitors, which are not suitable for integrated circuit implementation. In [2][3][4][5][6][7], the operation requires at least two active elements and three passive components. In [8,9], quadrature oscillators consist of a single active element and at least three passive components.In this paper a sinusoidal quadrature oscillator is designed with two active elements and two grounded capacitors, which is an advantage from the integration point of view. The oscillator circuit is designed with G m -C topology. A simple operational transconductance amplifier (OTA) and an improved floating current source (FCS) is used to provide g m value. The proposed quadrature oscillator is simulated with LTSPICE using the 0.18 µm TSMC CMOS process. Thus, the utility of the proposed circuit is verified.