We investigate the uncertainty of large-signal measurements of a microwave transistor due to variation in the load conditions at the fundamental frequency. In particular, we evaluate uncertainties in the complex frequency-domain traveling voltage waves. In our analysis, uncertainty sources typical for large-signal measurements are considered. Then, we discuss how the resultant uncertainty in the waves is dependent on a varying load reflection coefficient. For this investigation, we consider the total uncertainty of the waves and their magnitude and phase. We also show that these errors unavoidably affect the uncertainty of performance quantities, such as output power.
Keywords: Calibration; large-signal measurements; load–pull; measurement uncertainty; sensitivity analysis; vector network analyzer.