Describing functions and oscillators

In this article the "Describing Function" technique is applied to the analysis and design of oscillators. It is shown that, with some simplifications of the expressions involved in the analysis, this technique allows one not only to quantify the amplitude but also to determine the degree of distortion of the generated sinusoidal signal. The advantage of the describing function is that it allows the inclusion of the nonlinear behavior of a system while maintaining the simplicity often associated with the linear system analysis. This will be demonstrated through an example presenting the analysis and design of a sinusoidal oscillator in the frequency domain. The method as such allows formulation of closed-form expressions for the amplitude and distortion levels in much the same way classical linear techniques are used