An analytical charge control model for sheet carrier density is presented for InAlAs/InGaAs/InAlAs double heterostructure high electron mobility transistor (DH-HEMT). The model uses a polynomial dependence of sheet carrier concentration on position of quasi-Fermi energy level to successfully predict the gradual saturation of charge in the device and is valid from subthreshold region to high conduction region for both the channels. The model has been extended to calculate I-d-V-d characteristics, transconductance and cut-oft frequency of the device. (C) 2004 Elsevier Ltd. All rights reserved.