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Active and Passive Electronic Components
Volume 2011 (2011), Article ID 320367, 4 pages
Research Article

Quadrature Oscillators Using Operational Amplifiers

Department of Electronic Engineering, Chung Yuan Christian University, Chung-Li 32023, Taiwan

Received 19 May 2011; Accepted 2 July 2011

Academic Editor: Ahmed M. Soliman

Copyright © 2011 Jiun-Wei Horng. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Two new quadrature oscillator circuits using operational amplifiers are presented. Outputs of two sinusoidal signals with 90° phase difference are available in each circuit configuration. Both proposed quadrature oscillators are based on third-order characteristic equations. The oscillation conditions and oscillation frequencies of the proposed quadrature oscillators are orthogonally controllable. The circuits are implemented using the widely available operational amplifiers which results in low output impedance and high current drive capability. Experimental results are included.