Junction Field-Effect Transistors (JFETs)

<Operation of JFETs>
JFET : Junction Field-Effect Transistor
(1) In the N-channel junction field-effect transistor (Fig. 3-3 (a)), when a voltage is applied between the drain and the source, electrons flow from the source to the drain.
(2) When a reverse bias is applied between the gate and source, the depletion layer expands and suppresses the electron flow in (1). (Narrowing path of electron flow)
(3) If the reverse bias voltage between the gate and source is further increased, the depletion layer blocks the channel and the flow of electrons stops.

As shown above, voltage applied between gate and source controls the condition between drain and source. So FETs are voltage-driven devices.

Symbol and operation of N-channel-type JFET
Fig. 3-3(a) Symbol and operation of N-channel-type JFET
Symbol and operation of P-channel-type JFET
Fig. 3-3(b) Symbol and operation of P-channel-type JFET

Note: Direction of current flow is opposite to that of  electron flow. The mechanism of widening of the depletion layer is the same as for diode.

Chapter III : Transistors

Types of Transistors
Bipolar Transistors (BJTs)
Bias Resistor Built-in Transistors (BRTs)
Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs)
Differences between BJT and MOSFET
Structure and Operation of MOSFET
MOSFET Performance Improvement: Decision Factors of RDS(ON)
MOSFET Performance Improvement: Approach to Low RDS(ON)
MOSFET Performance Improvement: Super-Junction MOSFETs (SJ-MOS)
Summary of MOSFET Features by Structure
Performance of MOSFETs: Drain Current and Power Dissipation
Performance of MOSFETs: Avalanche Capability
Performance of MOSFETs: Characteristic of Capacitance
Performance of MOSFETs: Safe Operating Area(or Area of Safe Operation)
Insulated-Gate Bipolar Transistors (IGBTs)
Operation of Insulated-Gate Bipolar Transistors (IGBTs)
Performance Improvement of IGBTs: Evolution of Vertical Design
What are RC-IGBTs and IEGTs?
Application of IGBTs
Comparison of Forward Characteristics of IGBTs and MOSFETs
Comparison of Transistors by Structure
Datasheets of MOSFET: Maximum Ratings
Datasheets of MOSFET: Electrical Characteristics
Datasheets of MOSFET: Capacitance and Switching Characteristics
Datasheets of MOSFET: Body Diode

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