A PIECEWISE LINEAR APPROXIMATION FOR OUTPUT CHARACTERISTIC FOR SHORT-CHANNEL 'EXTRINSIC' MOSFET WITH ACCOUNTING OF NONZERO DIFFERENTIAL CONDUCTANCE IN SATURATION REGIME AND SOURCE PARASITIC RESISTANCE EFFECT AT HIGH DRAIN BIASES

摘要

Previously, we transformed the linear drain bias asymptote equation for the MOSFET drain current in the saturation regime from the "intrinsic" (without accounting for the contact and parasitic series resistances) case into "extrinsic" (with accounting for the contact and parasitic series resistances) case with accounting for the velocity saturation effect. As a result, we obtained the equation for the drain current that yielded the nonlinear dependence on the "extrinsic" drain bias for the short-channel "extrinsic" MOSFET in saturation regime in an implicit form. This equation can be solved numerically in the entire range of the "extrinsic" drain bias. Using this extrinsic equation, we derived the equation for the differential conductance of the "extrinsic" MOSFET at the "saturation point". Such "saturation point" is determined by the saturation current and saturation voltage equations for the "extrinsic" MOSFET that are well known from literature. We proposed a linear approximation for the dependence of the short-channel "extrinsic" MOSFET drain current on the "extrinsic" drain bias in the saturation regime. This approach works well for not very high drain bias.