Elementary deterministic theories of frequency and amplitude stability in feedback oscillators

First, the linear theory of frequency stability when applied to nearly sinusoidal feedback oscillators is critically reviewed. In this respect, a definition of the so-called linear oscillator is clarified. Then, the describing-function method and the Chua and Tang approach are applied to obtain new expressions for the oscillation-frequency and oscillation-amplitude stability of feedback oscillators considered as nonlinear networks.