Power Consumption of a MOSFET

by Frederick Selkey

Submitted : Spring 2010

A MOSFET is defined as metal oxide semiconductor field effect transistor. These are electrical devices that are combined or integrated together to form the control and logic functions for laptop and desktop computers, for power control in physical printing devices, in motor controls, and many other electrical circuits. As with all electrical devices, they consume electricity based on the values of current and voltage. For this paper we examine how to determine the energy consumption of a mosfet. Power consumption equals the current times the voltage. Calculus provides the tools to determine this value. The integral of a function in the I-V plane is the area under the characteristic. The area under an I-V curve will provide the value of this product. The first step is to take the function of a mosfet in the I-V plane derive the integral. The integral is then evaluated from a voltage when the device is considered to be turned off to a voltage when the device is considered to be turned on. Then we find the function's constant. Manufacturer data sheets provide the device's maximum electrical ratings and not the values of the physical properties of the device. These values are needed to determine the constant. To find this constant we set the evaluated integral equal to the maximum power dissipation according to the data sheet. The equation is then solved for the constant k. After the constant of a particular mosfet is known, the power dissipation for any Drain-Source and Gate Voltage can then be determined.

[ Back ]