Aim: To study the V-I characteristics of MOSFET
Apparatus Required: MOSFET Bread board Resistor Two Voltage Sources Connecting Wires
Theory: MOSFT stands for Metal Oxide Semiconductor Field Effect Transistor. It is actually a four terminal device whose substrate terminal must be always hold at one of the extreme voltage in the circuit either the most positive for PMOS or the most negative for NMOS. One unique property of MOSFET is that the gate drains no measurable current. The body of any N-channel MOSFET is made up of P-type material. 2 N-type materials are diffused at the top. A depletion region will be formed in the PN junction. A metal contact is made at the bottom of the P-type substrate and a terminal is taken out called the body or substrate. Similarly, a metal contact is made at the top of both the N-type materials, and two terminals are taken out as Drain and source. A Silicon dioxide layer is drawn in between the two N-type wells at the top. A metal contact is made at the top of it and a terminal is taken out called a Gate terminal. MOSFET is used as a high-frequency amplifier, brushless DC motor drives, electronic DC relays, inverter. The voltage at which the channel of the MOSFET closes is called the “pinch-off voltage”. When VDS is increased beyond the pinch-off voltage, VGS controls the channel current and VDS has little or no effect i.e. remains constant.
