Transistors - JFETs are solid-state four-terminal semiconductor devices designed for use as electronic control switches, resistors, or to create amplifiers. JFET stands for junction field-effect transistor, and is also called JUGFET. The terminals are known as a drain, gate, source, and body, where the body terminal is always linked to the source terminal. They are virtual devices that carry a majority charge due to their low noise. In addition, they feature high input impedance with low power consumption.
Types of Transistors - JFETs:
These semiconductors have two types of junctions/channels: N-Channel and P-Channel.
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N-Channel JFET Construction:
N-Channel semiconductors act as a base doped with P-type semiconductors at both ends. The N-Channel means that the electronic component constitutes the majority of the charge. An ohmic contact on the gate electrically connects these two P regions. The additional two terminals are removed at opposite ends to get the drain and source.
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P-Channel JFET Construction:
The name P-Channel indicates that the holes constitute a majority of the charge. A P-type semiconductor is employed as a base doped with an N-type channel at both ends to construct the P-Channel. Unlike N-Channel, both N regions are electrically connected at the gate with an ohmic contact, followed by removing the other two terminals at opposite ends to get the drain and source.
Why are Transistors - JFETs important?
These devices offer various benefits with remarkable features, including:
- A high degree of isolation between the input and the output
- High input impedance
- Voltage-controlled device and feature less noise.
Difference between JFET and BJT:
The main difference between JFET and BJT is that JFET’s output current is controlled by applied input voltage, while in BJT, the base current controls its output current.
What is the doping of semiconductors?
Doping is the process that adds foreign impurities to an intrinsic semiconductor device for modulating or enhancing its optical, structural, or electrical properties. The trivalent atoms used in the doped silicon result in the intrinsic semiconductor becoming a P-type semiconductor. The pentavalent substance used to dope the silicon triggers the intrinsic semiconductor to become an N-type semiconductor.
Applications of Transistors - JFETs:
JFET transistors are used as electronically controlled switches to control electric power to a load. They are also used as a phase shift oscillator. They also have various applications in:
- Electronics
- Communication
- Amplifiers.
