We present a spectrally-dense phase-reference and its calibration for nonlinear vector network analyzers (NVNAs) using a step recovery diode (SRD) comb-generator with a multi-tone stimulus. Frequency selection for multi-tone stimulus based on prime number algorithms was used with the Digital Real-Time Oscilloscope (DRTO) to avoid the sub-Nyquist spurs components and to increase the effective sampling rate so that the waveform can be observed in greater detail. The measured results were calibrated to minimize drift and jitter and achieved excellent agreement between the prime number and the exact frequency strategies except at the sub-Nyquist frequencies. The analysis indicates that the prime number selected frequencies show significantly improved performance by avoiding the DRTO distortion components. We have verified the validity of the method described in this paper by experimental measurement results. View Full-Text
Bibliographical noteShorter version presented by D A Humphreys at CPEM 2018. He Yu was a PhD Student at Harbin. She performed the measurements and I provided some guidance on my original analysis work.
- digital real-time oscilloscope (DRTO)
- harmonic phase-reference
- prime number algorithm
- sub-Nyquist spurs
- nonlinear vector network analyzer (NVNA)