What is phase noise?

Phase noise is a measure of the short-term frequency stability of a signal. It describes the random fluctuations in the phase of a waveform, typically expressed as a power spectral density (PSD) function of frequency offset from the carrier. Phase noise is crucial in applications like oscillators, synthesizers, and communication systems, where it can degrade signal quality, increase bit error rates, and limit system performance. Minimizing phase noise is often a key design consideration in these areas.