A Nonlinearized Lumped-Charge Model for Power Semiconductor Devices

The lumped-charge (LC) technique is widely used to develop simple and physically based power device models for circuit simulators. The existing models, due to the linearization of the diffusion equations in the drift region, have some limitations that impact accuracy and numerical stability. In this work, the carriers' transport equations, rather than linearized, are treated as differential equations, and an LC model that exactly solves the diffusion equations is presented. It improves the accuracy of the traditional models and provides a numerically stable expression of the currents while keeping the same simplicity. Furthermore, the continuity equations are rigorously discretized by means of the box integration method, widely used in finite element device simulators, which has been proven to be numerically stable and accurate. The new model is verified both on the static and transient characteristics of commercial insulated-gate bipolar transistors and power diodes.