3. Junction Field Effect Transistors (JFETs)
The Junction Field Effect Transistor (JFET) is a voltage-controlled unipolar device primarily used for amplifying or switching signals. Unlike bipolar junction transistors (BJTs), JFETs rely on gate voltage to control the drain current. This chapter explains the construction, working principles, biasing, and characteristics of JFETs, along with their applications, advantages, and disadvantages.
Sections
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What we have learnt
- JFET is a voltage-controlled, unipolar device.
- It operates in three regions: Ohmic, Active, and Cut-off.
- Gate voltage controls current through the reverse-biased depletion region.
- JFET offers high input impedance and low noise, making it ideal for signal processing applications.
Key Concepts
- -- JFET
- A Junction Field Effect Transistor is a voltage-controlled unipolar device used for amplifying or switching signals.
- -- Ohmic Region
- The range of operation where the JFET acts like a variable resistor when V_DS is small.
- -- Saturation Region
- The operating state of the JFET where I_D is constant and the device acts as an amplifier.
- -- Cutoff Region
- The state where the channel is closed, resulting in negligible drain current.
- -- Transfer Characteristics
- A plot of drain current versus gate-source voltage characterized by Shockley's Equation.
Additional Learning Materials
Supplementary resources to enhance your learning experience.