A HEMT physical model for CAD

The new implementation of a Quasi-two Dimensional HEMT model presented in this paper has for the first time made it possible to predict device pinch-off at high drain bias. This has been possible with the inclusion of a new analytical description for the injection of carriers into the buffer/substrate regions of the device. The equivalent circuit, extracted from the S-parameter simulation, shows no spurious responses and exhibits the correct variation with applied gate and drain bias. The execution time of the simulations remains extremely fast due to the inclusion of the analytical substrate injection model and asymptotic boundary condition which together greatly reduce the size of the charge-control look-up table that needs to be simulated. For this reason the model is well suited to the consideration of large signal device/circuit design and yield driven design