Characterization of MOS transistor current mismatch

Electron device matching has been a key factor on the performance of today's analog or even digital electronic circuits. This paper presents a study of drain current matching in MOS transistors. CMOS test structures were designed and fabricated as a way to develop an extensive experimental work, where current mismatch was measured under a wide range of bias conditions. A model for MOS transistor mismatch was also developed, using the carrier number fluctuation theory to account for the effects of local doping fluctuations. This model shows a good fitting with measurements over a wide range of operation conditions, from weak to strong inversion, from the linear to the saturation region, and allows the assessment of mismatch from process and geometric parameters.