Saif-ur REHMAN, Umer Farooq AHMED, Muhammad Mansoor AHMED, Umair RAFIQUE

An improved space charge distribution analytical model to assess field-effect transistor’s intrinsic capacitors

In this paper, an analytical model has been developed for improved assessment of Miller capacitors for highfrequency metal–semiconductor field-effect transistors. Depletion layer underneath the Schottky barrier gate has beendivided into four distinct regions, and by evaluating the charges associated with each region, gate-to-source (CGS ) andgate-to-drain (CGD ) capacitors, commonly known as Miller capacitors, have been defined accordingly. Mathematicalexpressions have been developed both for the linear as well as for the saturation region. Miller capacitors and theirvariation as a function of applied bias have been assessed. It has been shown that the proposed technique offers betteraccuracy in determining the Miller capacitors, especially CGD of the device relative to other reported analytical capacitormodels. This improved accuracy has been achieved by involving the entire Schottky barrier depletion layer piecewisefor the assessment of charges defining the Miller capacitors. Thus, the developed technique could be a useful tool inassessing the AC response of the device with more precision.

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