On-Wafer Oscilloscope-Based Nonlinear Characterisation: Benchmarking Against NVNA Measurements

This paper benchmarks an on-wafer real-time oscilloscope (RTO) setup for obtaining corrected time domain <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$a$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${b}$</tex> waves of two-port devices operating under steady-state continuous-wave large-signal conditions. Comparison to Nonlinear Vector Network Analyser (NVNA) measurements validated the usability of the RTO. An RTO can capture transients, crucial for understanding non-steady state behaviour, an analysis not possible with NVNAs due to their mixer-based architecture. The calibration procedure is detailed and RTO measurements of unmatched GaN-on-Si HEMTs at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${f}_{\mathrm{0}} = 13 \text{GHz}$</tex> are compared to NVNA measurements. Discrepancies between results are due to differences in device performance from stress, internal RTO hardware behaviour, and source and load match variations from probing and test-set differences. VNA load-pull confirmed DUT sensitivity to the load match. The results demonstrate the potential of RTO setups for nonlinear characterisation beyond the limitations of NVNAs.