Phase noise analyzing system that analyzes phase noise in radio frequency (RF) signals provided by a device under test when coupled thereto includes a low noise receiver that receives at a first input, signal from the device under test when coupled thereto, a low noise synthesizer that provides output to the receiver, a frequency domain analyzer that receives output from the receiver, a time domain analyzer that receives output from the receiver, a switching system that controls signal flow to and from the receiver, the synthesizer, the frequency domain analyzer and the time domain analyzer, and a computer that controls the switching system to perform the analysis of phase noise in signals provided by the device under test.