Phase calibration for coherent multi-harmonic modulated signal measurements using nonlinear vector network analyzer

This paper proposes a novel phase calibration approach to enable multi-harmonic modulated signal measurements using existing nonlinear network analyzer (NVNA) receivers configured in wideband mode. The envelopes around the harmonics are captured sequentially so that the dynamic range (DR) of the measurement system is not compromised. A reference signal generated by a comb generator is used to ensure phase coherency between the harmonics, precluding the need to use a small frequency grid that typical solutions require. To validate its ability to make accurate measurements of multi-harmonic modulated signals, the proposed NVNA-based method is tested against a state-of-the-art oscilloscope. The proposed approach is applied first to an 8-tone signal that covers 14 MHz, then on a 5 MHz 1C-WCDMA signal. Both signals have three harmonics with the fundamental frequency at 1 GHz. The phase accuracy of the measured signal is within ±1.5° and ±10° for the first and second test signals, respectively.