Parametric hysteresis in power amplifiers

Parametric hysteresis in power amplifiers is investigated, studying the causes of this phenomenon and providing an efficient methodology for its prediction and elimination. As will be demonstrated, in MESFET and HEMT devices it is caused by a nonlinear resonance of the device input capacitance under near optimum input matching conditions. Bifurcation loci are used to evaluate the impact of the phenomenon under variation of critical design parameters. All the tests have been carried out in a Class -E GaN PA with measured 86.8% PAE and 12.4W output power at 0.9 GHz .