FFT and Swept Spectrum Analysis in Microwave Measurements

Accuracy, speed, and dynamic range are important considerations, among which tradeoffs are typically made for a given measurement. We present that FFT (fast Fourier transform) spectrum analysis is inherently less accurate than Swept Spectrum Analysis with a digital IF (intermediate frequency) section. For phase noise-like dynamic range considerations, we describe FFTs as having more noise than Swept Analysis. When speed is the driving factor we present FFTs as the technique of choice for narrow-band analysis, while swept analysis is substantially faster for wider bandwidths. Finally, a novel continuum between the performance of swept and FFT analysis is also presented.