Presentation on MOSFET.pptx basic of mosfet in
- 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
- 5. Key Parameters • Threshold Voltage (Vth): The minimum gate-to- source voltage required to turn on the MOSFET. • Drain-Source On-Resistance (RDS(on)): The resistance between drain and source when the MOSFET is on. • Maximum Drain Current (ID(max)): The maximum current that can flow through the drain. • Breakdown Voltage (VBR): 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.
- 7. Regions of Operation 1. Cut-off Region (VGS < VTH): • The MOSFET is off, and there is no current flow between drain and source (except for leakage current). 2. Ohmic (Linear) Region (VGS > VTH, VDS < VGS - VTH): • The MOSFET operates like a variable resistor. • The current through the MOSFET increases linearly with the increase in VDS. 3. Saturation (Active) Region (VGS > VTH, VDS ≥ VGS - VTH): • The MOSFET operates as a constant current source. • The current through the MOSFET is mostly independent of VDS_{DS}DS and is controlled by VGS.
- 8. N-Channel Enhancement Mode MOSFET 1. Off State (VGS < VTH): • Gate-Source Voltage (VGS) is less than the threshold voltage (VTH). • 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 (VGS > VTH): • Gate-Source Voltage (VGS) is greater than the threshold voltage (VTH). • 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
- 9. P-Channel Enhancement Mode MOSFET 1. Off State (VGS > VTH): • Gate-Source Voltage (VGS) 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 (VGS < VTH): • Gate-Source Voltage (VGS) 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 (VDS) 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.