Introduction To Phase Noise In Signal Generators

By Leonard Dickstein, Giga-tronics Incorporated

The literature on phase noise is vast, (much of it quite esoteric) and too numerous to list. This introduction to phase noise is a compilation with the intent of providing an intuitive understanding of phase noise as it applies to microwave signal generators.

Phase Noise is an Attribute of All Real World Signals

Phase noise is the result of small random fluctuations or uncertainty in the phase of an electronic signal. We specify and measure phase noisebecause it is a fundamental limitation in the performance of systems, limiting dynamic range. This shows up in radar and communications as loss of sensitivity, in imaging as lack of definition and in digital systems as higherbit error rate. While this discussion will focus primarily on phase noise in the frequency domain, phase noise can also be quantified as jitter in the time domain.