Presentation on MOSFET.pptx basic of mosfet in

mosfet basic ppt

1. Mosfet

2. Introduction A Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) is a type of transistor used for amplifying or switching electronic signals. The working principle of a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is based on controlling the conductivity between the drain and source terminals by varying the voltage applied to the gate terminal

3. Structure Gate (G): A conductive terminal insulated from the underlying semiconductor material by a thin layer of oxide. Drain (D): The terminal through which the current flows out. Source (S): The terminal through which the current enters. Substrate (Body): The main semiconductor material (usually silicon).

4. Types of Channel 1. N-Channel MOSFETs: Description: Electrons are the charge carriers. They turn on with a positive gate voltage relative to the source. Advantages: Typically have lower on-resistance and higher electron mobility, making them more efficient for high-speed and high-current applications. 2. P-Channel MOSFETs: Description: Holes are the charge carriers. They turn on with a negative gate voltage relative to the source. Usage: Often used in complementary MOSFET circuits (CMOS) with N-channel MOSFETs

5. Key Parameters Threshold Voltage (V th ): The minimum gate-to-source voltage required to turn on the MOSFET. Drain-Source On-Resistance (R DS(on) ): The resistance between drain and source when the MOSFET is on. Maximum Drain Current (I D(max) ): The maximum current that can flow through the drain. Breakdown Voltage (V BR ​): The maximum voltage the MOSFET can handle before it breaks down.

6. Working Modes 1. Enhancement Mode MOSFETs (E-MOSFETs): Description: These are normally off at zero gate voltage. They require a positive gate voltage (for N-channel) or a negative gate voltage (for P-channel) to turn on. Usage: Commonly used in digital circuits and power switching applications. 2. Depletion Mode MOSFETs (D-MOSFETs): Description: These are normally on at zero gate voltage. They require a negative gate voltage (for N-channel) or a positive gate voltage (for P-channel) to turn off. Usage: Less common, used in specialized analog applications

7. Regions of Operation 1. Cut-off Region (V GS ​ < V TH ): The MOSFET is off, and there is no current flow between drain and source (except for leakage current). 2. Ohmic (Linear) Region (V GS ​ > V TH ​, V DS ​ < V GS ​ - V TH ​): The MOSFET operates like a variable resistor. The current through the MOSFET increases linearly with the increase in V DS . 3. Saturation (Active) Region (V GS > V TH ​, V DS ​ ≥ V GS - V TH ): The MOSFET operates as a constant current source. The current through the MOSFET is mostly independent of VDS_{DS}DS​ and is controlled by V GS​ .

8. N-Channel Enhancement Mode MOSFET 1. Off State (V GS ​ < V TH ): Gate-Source Voltage (V GS ) is less than the threshold voltage (V TH​ ). No conductive channel forms between the drain and source. The MOSFET is in the "off" state and does not conduct current (except for a small leakage current). 2. On State (V GS ​ > V TH​ ): Gate-Source Voltage (V GS ) is greater than the threshold voltage (V TH ). An electric field induces a conductive channel (inversion layer) in the semiconductor material between the source and drain. Electrons (charge carriers) flow from the source to the drain when a voltage (VDS_{DS}DS​) is applied across the drain and source, enabling current flow through the MOSFET

9. P-Channel Enhancement Mode MOSFET 1. Off State (V GS ​ > V TH​ ): Gate-Source Voltage (V GS​ ) is less than the threshold voltage (negative value for P-channel). No conductive channel forms between the drain and source. The MOSFET is in the "off" state and does not conduct current (except for a small leakage current). 2. On State (V GS ​ < V TH​ ): Gate-Source Voltage (V GS​ ) is less than the threshold voltage (negative value for P-channel). An electric field induces a conductive channel in the semiconductor material between the source and drain. Holes (charge carriers) flow from the source to the drain when a voltage (V DS ​) is applied across the drain and source, enabling current flow through the MOSFET

10. Advantages High input impedance. Fast switching speeds. Low power consumption.

11. Applications Switching: Used in power supplies, motor controllers, and digital circuits. Amplification: Used in audio amplifiers and RF amplifiers. Analog Circuits: Used in voltage regulators and analog signal processing.

12. Conclusions MOSFETs are crucial components in modern electronics due to their efficiency and versatility. Their ability to handle high-speed switching and low power operation makes them ideal for various applications in both analog and digital electronics.