Dynamic-Bias S-Parameters: A New Measurement Technique for Microwave Transistors

We present the first application of the recently introduced dynamic-bias measurement to the acquisition of the scattering (S-) parameters of microwave transistors under large-signal operating conditions. We demonstrate that by properly acquiring and processing dynamic-bias measurements, one can derive the S-parameters of a nonlinear device-under test across a time-varying large-signal operating point (LSOP). Interestingly, these time-varying S-parameters can be used similar to the conventional S-parameters for characterization and modeling purposes. As compared with similar existing approaches, like those based on the pulsed S-parameter measurements, with the proposed technique, one can obtain, as a result of one measurement, the frequency-dependent S-parameters at each instantaneous point touched by the LSOP. We report experimental dynamic-bias S-parameters of a 0.15-μm GaAs pHEMT and a 0.25-μm GaN HEMT.