A measurement based gate current model for GaAs MESFET´s and HEMT´s including self-heating and impact ionization

We present a new gate current model to improve the simulation accuracy of power MESFET and HEMT characteristics. The model is designed to meet the demands of a circuit designer. By the use of a polynomial fit it predicts the gate current within the usual voltage range of an amplifier load line with the highest accuracy. In addition, this leads to a much better simulator convergence than the conventional exponential fit. It also includes the critical on-state breakdown effects that are overlooked by usual gate current models. The model is split into two parts, one equation describes the current caused by tunneling and thermionic emission and another equation describes the impact ionization current. This gives insight into the device physics and allows independent thermal modeling of both effects