Key Takeaways
- The Field-Effect Transistor (FET) is a crucial electronic component used in various applications, particularly amplification and switching circuits.
- The Bipolar Junction Transistor (BJT) is a fundamental electronic device used in various applications.
- FETs have high input independence, drawing minimal current from the input source. In contrast, BJTs have lower input independence as they require a significant base current to control the collector-emitter.
What is FET?
The Field-Effect Transistor (FET) is a crucial electronic component used in various applications, particularly amplification and switching circuits. It belongs to the family of transistors along with BJT.
An FET consists of three terminals- the source, the gate, and the drain. They are voltage-controlled devices which operate based on the voltage applied to the gate terminal. FETs generate minimal heat and have a faster switching speed, making them ideal for digital circuits.
The operation of a FET is based on controlling the flow of charge carriers between the source and drain terminals by varying the voltage on the gate terminal. They offer several advantages. They have high input impedance, drawing minimal current from the input source, making them suitable for high-frequency applications.
What is BJT?
The Bipolar Junction Transistor is a fundamental electronic device used in various applications. It is one of the two main types of transistors. A BJT consists of three layers of semiconductor material: the emitter, base, and collector. There are two main types of BJTs: Negative-positive-negative (NPN) and Positive-negative-positive (PNP).
The operation of a BJT is based on the movement of charge carriers across the transistor’s layers. In an NPN transistor, a small current flows into the base terminal, allowing a more substantial current to flow from the collector to the emitter.
BJTs have certain advantages. They can provide significant current gain, making them ideal for applications where signal application is required, such as in audio amplifiers.
They are essential components in electronics, especially in analogue amplification circuits. They are current-controlled devices with NPN and PNP configurations, offering significant current gain but consuming more power and generating heat.
Difference Between FET and BJT
- FETs are voltage-controlled devices that regulate current flow between the sources and drain terminals based on the voltage applied to the gate terminal. At the same time, BJTs are current-controlled devices as they control the current flow between the collector and emitter terminals by adjusting the current flowing into the base terminal.
- FETs have high input independence, drawing minimal current from the input source. In contrast, BJTs have lower input independence as they require a significant base current to control the collector-emitter.
- FETs consume less power because they have minimal gate currents, while BJTs consume more power as they require base currents to operate.
- FETs are well suited for voltage amplification due to their high input independence, while BJTs are better suited for current applications due to their current gain, such as analogue amplifiers.
- FETs have fast switching speeds, making them suitable for digital applications and high-frequency circuits, while BJTs have comparatively slower switching speeds.
ComparisonBetween FET and BJT
| Parameters | FET | BJT |
|---|---|---|
| Control Mechanism | Voltage-controlled devices as regulate current flow between the sources and drain terminals | Current controlled devices as they control the flow of current flow between the collector and the emitter |
| Input Independence | High as they draw little current from the input source | Lower as they require significant base current to control |
| Power Consumption | Less power due to minimal gate current | More power as they need base current to operate |
| Voltage vs. current Amplification | Well suited for voltage amplification | Better suited for current amplification |
| Speed | fast | slow |
- https://www.sciencedirect.com/science/article/pii/002626929390102K
- https://ieeexplore.ieee.org/abstract/document/1191766/
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