Multiharmonic generators for relative phase calibration of nonlinear network analyzers

Multiharmonic generators are of interest for determining coupler phase dispersion of nonlinear network analyzers inherently dealing with nonsinusoidal waveforms for RF current-voltage (I-V) measurements. Supported by simple waveform analysis, two on-wafer devices are experimentally evaluated: a single diode and a nonlinear transmission line (NLTL). The investigation uses an active harmonic load-pull system with 2 GHz fundamental frequency. It turns out that the NLTL is well suited as a reference generator. We present measurement examples of phase dispersion for different directional couplers up to 18 GHz and the application to RF I-V waveforms of a 1-W power HBT with harmonic load tuning.