Millimeter-Wave FET Nonlinear Modelling Based on the Dynamic-Bias Measurement Technique

In the paper, the nonlinear model of a microwave transistor is extracted from large-signal measurements acquired under “dynamic-bias” operation. Specifically, the transistor is driven by low-frequency large signals while a high-frequency tickle is applied on top of them. The low-frequency large signals, along with the dc bias voltages, set the large-signal operating point which represents a dynamic-bias condition for the device under test. Thanks to this technique, one can get at once and separately the nonlinear currents and charges of the transistor as a result of a very few nonlinear measurements. Additionally, the proposed technique allows one to accurately reconstruct the time-domain waveforms at the device-under-test terminals while the frequency of the tickle can be set as high as the bandwidth of today's vector calibrated nonlinear measurement systems (i.e., 67 GHz). The approach, which is general and independent of device technology, is applied on a 0.15- μm GaAs pHEMT specifically designed for resistive cold-FET mixer applications.