A NEW CAD ORIENTED CHARGE CONSERVING CAPACITANCE MODEL FOR HEMTS

We present a new analytical charge conserving capacitance model for hi gh electron mobility transistors (HEMTs) based on the quasi-static app roximation and a proper partitioning of the channel charge between the source and the drain terminals. Simple analytical expressions for thr ee terminal charges (Q(g), Q(d), and Q(s)) were derived by integrating the sheet charge density over the gate length. This leads to a total of nine so-called transcapacitances by taking derivatives of the termi nal charges with respect to the voltages at three nodes. The nine tran scapacitances can be organized into a 3 x 3 matrix obeying Kitchhoffs current law and independence of reference. The transcapacitances are n on-reciprocal in nature, i.e. Cij not equalCji. when i not equal j. Th e model is valid both above and below threshold and shows good agreeme nt with experimental data. 1998 Published by Elsevier Science B.V. All rights reserved.