Measurement of standard deviation of threshold voltage by using parallel-connected MOSFETs

Abstract

A test circuit in which many MOSFETs of identical structure are parallel connected is proposed for measuring the standard deviation of MOSFET threshold voltage. The threshold voltage, which is extracted from the drain-current versus gate-voltage (IDS-VG) characteristic for this test circuit, differs from the average value of those for the individual MOSFETs included in this test circuit by an amount that depends on its standard deviation. Using this fact, the standard deviation of the threshold voltage can easily be measured. This paper describes the measurement principle, establishes its verification using IDS-VG characteristics for experimental MOSFETs, and discusses its accuracy. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 2,80(1): 11–17, 1997