Conditions for Oscillator Small-Signal Amplitude-Phase Orthogonality

The paper explores a previously unknown connection relating the symmetry properties of an oscillator steady-state to the orthogonal representation of amplitude and phase variables in the small-signal regime. It is shown that only circuits producing perfectly symmetric steady-states can produce an orthogonal Floquet decomposition. Considering room temperature operation this scenario implies zero AM-PM noise conversion. This surprising and novel result follows directly from the predictions of a rigorous model framework first described herein. The work presented in this text extend the current state-of-the-art w.r.t. oscillator small-signal/noise characterization.