Difference between MOSFET and BJT
The key differences between MOSFET and BJT are:
| Feature | MOSFET | BJT |
|---|---|---|
| Full Form | Metal-Oxide-Semiconductor Field-Effect Transistor | Bipolar Junction Transistor |
| Structure | Three-terminal device: Source, Drain, Gate | Three-terminal device: Collector, Base, Emitter |
| Principle of Operation | Majority carrier device: controlled by gate voltage | Minority carrier device: controlled by base current |
| Current Carrying Mechanism | Majority carrier (electrons or holes) | Minority carrier (holes or electrons) |
| Input Impedance | High (insulated gate) | Low (input current controls output current) |
| Output Impedance | Moderate to High (depends on circuit) | Low (depends on circuit) |
| Switching Speed | Faster | Slower |
| Gain | Voltage-controlled | Current-controlled |
| Saturation Voltage | Typically lower (near 0V) | Typically higher (around 0.2V to 0.7V) |
| Temperature Sensitivity | Low | Moderate to high |
| Thermal Stability | Generally more stable | Less stable |
JFET and MOSFET
Common differences between JFET and MOSFET are:
| Feature | JFET | MOSFET |
|---|---|---|
| Full Form | Junction Field-Effect Transistor | Metal-Oxide-Semiconductor Field-Effect Transistor |
| Structure | Three-terminal device: Source, Drain, Gate | Three-terminal device: Source, Drain, Gate |
| Channel Type | Majority carrier device: controlled by gate-source voltage | Majority carrier device: controlled by gate-source voltage |
| Channel Composition | Semiconductor channel formed by reverse-biased pn-junction | Semiconductor channel formed by insulated gate |
| Gate Construction | No insulating layer between gate and channel | Insulating layer (oxide) between gate and channel |
| Voltage Applied | Gate-source voltage controls channel conductivity | Gate-source voltage controls channel conductivity |
| Conductivity Control | Voltage-controlled resistor | Voltage-controlled resistor |
| Input Impedance | High (insulated gate) | High (insulated gate) |
| Output Impedance | Moderate to High (depends on circuit) | Moderate to High (depends on circuit) |
| Switching Speed | Faster than MOSFETs | Generally slower than JFETs |
| Voltage Ratings | Low to medium voltage applications | High voltage applications |
| Temperature Sensitivity | Moderate | Low |
| Thermal Stability | Generally more stable | Generally more stable |
MOSFET – Metal Oxide Silicon Field Effect Transistors
MOSFET or Metal-Oxide-Silicon Field-Effect Transistor is a type of field-effect transistor (FET) that is commonly fabricated using silicon. It features an insulated gate, the voltage of which determines the conductivity of the device. MOSFETs are used for amplifying or switching electronic signals and are known for their high input impedance, which results in high switching speed.
In this article, we will discuss MOSFET in detail including its types, working as well as application.
Table of Content
- What Is a MOSFET?
- Structure of MOSFET
- Working of MOSFET
- Types of MOSFET
- Applications of MOSFET
- Advantanges and Disadvantages of MOSFETs