  A new and simple analytical charge-control model of the two-dimensional
electron gas of a double-heterojunction AlGaAs/GaAs/AlGaAs HEMT is described.
It is found that, despite its simplicity, the charge-control model gives an
accurate description of the device operation for a wide range of physical
parameters. The validity of the analytical model is supported by the calculated
results of the self-consistent quantum mechanical model and agrees with
previously reported theoretical and experimental data. The influence of some
physical parameters on the device performance is also discussed.
