Dense Spectral Grid NVNA Phase Measurements Using Vector Signal Generators

This paper proposes a practical approach for dense-spectral-grid phase measurements based on a nonlinear vector network analyzer (NVNA). With the multitone outputs of commercial VSGs as both phase references and standards, a modified NVNA is presented to effectively obtain the phase spectra of modulated RF signals with spectral resolution of 1-100 kHz. Due to the limited tone number of a VSG multitone standard, a multistep phase calibration method is also proposed in this paper for multiplying the calibratable tone numbers in practice. A phase accuracy of ±2° has been experimentally achieved with both the VSG-based approach and the multistep phase calibration method at 2.4 GHz on a 1-100-kHz spectral grid.