Proportional difference operator method and its application in studying subthreshold behavior of MOSFETs

The proportional difference operator (PDO) method is presented to study the subthreshold behavior of MOSFETs. By applying the PDO, acting on an expres sion for the drain current in the subthreshold region, a new proportional d ifference characteristic of MOSFET can be obtained. The analytical results show that the proportional difference of the subthreshold equation is a pea k function. Its peak position, being dependent on the measurement voltage, is related to the characteristic parameters, so the most important paramete rs (such as thermal and threshold voltages) can be easily obtained. A surfa ce potential approximation has been developed and implemented in studying a MOSFET's proportional difference subthreshold behaviors. The relationships between the classical threshold voltage and the Lindner threshold voltage are also discussed. Values of voltage constants are shown to agree well wit h those obtained by standard methods. (C) 2000 Elsevier Science Ltd. All ri ghts reserved.