Drain-voltage dependence of IGFET turn-on voltage

Abstract The turn-on voltage (or threshold voltage) characteristic of an enhancement-type insulated-gate field-effect transistor (IGFET) in its pentode operation region, is analyzed based on a simple model. A new definition for the turn-on voltage at just-saturated state is given and a new simple formula for the turn-on voltage shift in IGFETs pentode operation region, is deduced. This assumes a reduction of gate-induced bulk charge under the influence of the drain voltage. Agreement of the theory with experiment is good.