FINDING THE ASYMMETRIC PARASITIC SOURCE AND DRAIN RESISTANCES FROM THE AC CONDUCTANCES OF A SINGLE MOS-TRANSISTOR

Layout asymmetry, processing, or hot-carrier stressing can give rise t o unequal source and drain parasitic resistances in a MOSFET. In these cases, it is necessary to extract these resistances separately withou t the aid of other transistors. In this paper, we present a simple met hod to extract the source and drain parasitic resistances separately. This method, unlike earlier ones that depend on the measurements of th e d.c. resistances of several MOSFETs, is based on accurate formulatio ns and measurements of the a.c. conductances with respect to the gate and drain terminals of a single transistor. This allows us to get reas onably accurate estimates of these resistances in a more straightforwa rd manner. We also discuss the main error terms in detail.