Cross-Spectrum Noise Measurements
白皮书
Theory of Cross-Spectral Collapse is explained theoretically and demonstrated with simulations and measurements, for both baseband noise and phase noise. AM-PM Source noise cancellation is derived and shown in simulations. The main counter measure to cross-spectral collapse is to improve isolation between the two channels of the cross correlation to reduce both correlated and anti-correlated system noise relative to the DUT noise. The channel delays should be minimized to increase spacing between cross spectral nulls, and for baseband noise to push them out to high frequencies.