A New NVNA Phase Reference for Polyharmonic Intermodulation Measurements

The step-recovery-diode-based impulse generator is a classical picosecond-level impulse-formation technique, whose strong harmonic nonlinearity under sinusoidal stimulus is widely utilized as the phase reference of the nonlinear vector network analyzer (VNA) (NVNA) and large-signal network analyzer for wideband measurements. This paper further exploits its intermodulation nonlinearity under multitone stimulus and proposes a new approach, rather than the traditional "harmonic" way, of the NVNA phase reference for future polyharmonic intermodulation measurements. Experimental results show that this method can provide plentiful intermodulation components around each harmonic available and is stable for NVNA use, with the advantages of flexible local frequency-resolution setup from tens of megahertz to less than hundreds of hertz.