New Amplitude Correction and Phase Linearization Technique for Channel Response on Wideband Microwave Spectrum Analysers

Channel frequency response is one of the banner performance specifications for discrete Fourier transform (DFT) based spectrum analysers. Digital techniques have emerged as most attractive approaches to correct the linear distortion introduced in the microwave and immediate frequency (IF) analogue signal paths. This paper presents a novel technique for correcting the channel frequency response (flattening amplitude and linearizing phase) on microwave spectrum analysers. By combining factory calibration data of the amplitude and phase response and run-time IF alignment, we can accomplish significant improvement in vector measurement performance. In contrast, traditional equalization of channel frequency response is only performed at a fixed IF frequency and the channel response variation over RF frequencies is mostly ignored. A cost-effective calibration solution can also be realized using an arbitrary waveform generator (AWG) and an off the shelf mixer to generate calibration signal.