Wien bridge oscillators: Are they always sinusoidal oscillators?

This paper shows that a Wien-bridge oscillator is not always a sinusoidal oscillator.Depending on the differential input voltage of the operational amplifier used, the output of the Wien-bridge oscillator can move from a nearly sinusoidal wave to a nearly square wave. This depends largely on the values of the passive components used. Experimental results that confirms the presented theory are included. These results confirm the previously made observations that sinusoidal oscillators and multivibrators are not separate classes of circuits as the same circuit can provide the two modes of operation depending on the values of the passive components used.