Comparison of classical and modified Wien oscillator circuits in term of existence of steady state oscillations

The Barkhausen well known criterion for generation of steady state harmonic oscillations is, due to its simplicity, very often used in a design of oscillators. In literature, however, there are examples of oscillator circuits that, even when this condition is met, they do not oscillate at a desired frequency. From these findings it follows that the Barkhausen criterion is only a necessary condition for steady state oscillations existence, however not a sufficient one. In order to further discuss this problem a classical and modified Wien oscillator circuits we analyzed and compared in frequency and time domain. From these investigations, we outline another necessary condition that has to be fulfilled for the existence of steady state oscillations.