A Square Wave and Sinusoidal Quadrature Oscillator Based-on LT1228

This article presents a square wave and sinusoidal quadrature oscillator. This oscillator consists of three active elements (LT1228) with two grounded capacitors and a grounded resistor. The condition of oscillation and frequency of oscillation are electronically adjusted without effect on each other. The frequency of oscillation is linearly controlled. Moreover, the amplitude of sinusoidal signals can be tuned by added two grounded resistors at x-pin of 1
^st
and 2
^nd
of LT1228. The experiment results are theoretically predicted that the output signals have the same amplitude, the deviation of the phase difference and frequency are not more than 3.1% and 3.3%, respectively, and the maximum harmonic distortion is -40.2dB (0.98%). With this feature, when adding resistor at x-pin on 3
^rd
LT1228, the proposed oscillator generates a square wave as well.