A Nonlinear Drain Resistance pHEMT model for Millimeter-wave High Power Amplifiers

Abstract

A high power pHEMT with longer drain-gate separation can operate at higher voltage. However, it shows large output power loss at millimeter-wave in addition to the conventional parasitic power dissipation. The nonlinear drain resistance Rd of the pHEMT is found to cause the large power loss, although it behaves as a conventional resistor at low frequency. The nonlinearity of the Rd is modeled and shows good agreement with the measurement. Comparisons of pHEMTs with different nonlinear Rd also support the model.