The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a device used for amplifying or switching electronic signals. This device is built on a substrate of p-type silicon. Two heavily doped n-type tubs are diffused in for the source (S) and the drain (D). Here, a voltage on the oxide-insulated gate electrode can induce a conducting channel between the two other contacts called source and drain.
The following schematic shows typical MOSFET Inverter Circuit Diagram. In this circuit, VDD = 6 volts and the circuit for input voltages of Vin = 0,3, and 6 volts. Solution of these circuits almost always involves finding the output voltage, which in this case is VO = VDS, the voltage between the drain and ground, or the current in the drain, ID.