2DEG Charge Density Calculation for HEMT Physics-Based Compact Models by Newton Method

This work proposes a physically based, High Electron Mobility Transistor (HEMT) model by directly implementing the implicit equation of the two dimensional electron gas (2DEG) charge density. To achieve this, four iterations of the Newton-Raphson algorithm, together with an appropriate initial value estimation, are embedded in the core model. This approach is effective for any applied gate voltage, particularly in the subthreshold region, without requiring behavioral manipulation of the model equations, as in conventional core models. The proposed model is continuously differentiable, up to any order, accurately. The proposed charge formulation is compared to the ASM model formulation. To show the capability, the model is implemented in Verilog-A to calculate the charge and then the drain current to compare with measurement data.