The AM noise mechanism in oscillators

The oscillator, inherently, turns the phase noise of its internal components into frequency noise, which results into a multiplication by 1/f
²
in the phase-noise power spectral density. This phenomenon is known as the Leeson effect. This article extends the Leeson effect to the analysis of amplitude noise. This is done by analyzing the slow-varying complex envelope, after freezing the carrier. In the case of amplitude noise, the classical analysis based on the frequency-diomain transfer function is possible only after solving and linearizing the complete differential equation that describes the oscillator.