AC model for MOS transistors from transient-current computations

It is shown how the terminal transient currents in an MOS transistor can be computed from analytical expressions together with the DC model under quasistatic conditions. The channel drift current is solved assuming that the increase in channel charges is supplied from source and drain contacts. Capacitances derived from our AC model agree closely with those in Ward´s model using an accurate channel charge partition ratio from numerical analysis.