Which of the following is NOT a type of Field Effect Transistor?
Thyristor
Understanding Different Types of Transistors
This question asks us to identify which option from the given list is NOT a type of Field Effect Transistor (FET). To answer this, we need to understand what a FET is and recognize the other types of electronic components listed.
What is a Field Effect Transistor (FET)?
A Field Effect Transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. They are voltage-controlled devices, meaning the voltage applied to the gate terminal controls the current flow between the source and drain terminals.
Common types of Field Effect Transistors (FETs) include:
- JFET (Junction Field-Effect Transistor): This is one of the simplest types of FETs. It uses a P-N junction to form the gate.
- MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor): This is the most common type of FET. It uses an insulator (usually silicon dioxide) between the gate and the semiconductor channel. MOSFETs are further categorized into:
- Depletion Mode MOSFET: This type has a channel present even with zero gate-source voltage. Applying a gate voltage can deplete (reduce) the channel conductivity.
- Enhancement Mode MOSFET: This type does not have a channel present with zero gate-source voltage. A gate voltage must be applied to create (enhance) the channel and allow current flow.
Looking at the options provided, JFET, Depletion MOSFET, and Enhancement MOSFET are all clearly identified as types of Field Effect Transistors (FETs).
What is a Thyristor?
A Thyristor is a different type of semiconductor device. Unlike transistors, which can operate in linear or switching modes and are voltage-controlled (FETs) or current-controlled (BJTs - Bipolar Junction Transistors), a thyristor is primarily used as a switch and is a latching device. Once triggered, it continues to conduct current until the current falls below a certain holding level or is turned off externally. Thyristors are typically four-layer devices (PNPN).
Examples of thyristor family devices include SCR (Silicon Controlled Rectifier), DIAC, and TRIAC. They are widely used in power control applications.
Comparing FETs and Thyristors
The key difference lies in their operation and control mechanisms:
- FETs: Voltage-controlled devices used for amplification and switching. They operate in linear, cutoff, and saturation regions.
- Thyristors: Primarily switching devices (latching switches). Once triggered, they remain ON until the current drops below a holding current, regardless of the gate signal (after triggering). They are used for high-power switching and control.
Based on this comparison, a Thyristor operates fundamentally differently from a Field Effect Transistor (FET) and belongs to a separate family of semiconductor devices.
Conclusion
The options list JFET, Depletion MOSFET, Enhancement MOSFET, and Thyristor. We have established that JFET, Depletion MOSFET, and Enhancement MOSFET are all types of Field Effect Transistors. A Thyristor is a different type of semiconductor power switch.
Therefore, the component that is NOT a type of Field Effect Transistor is the Thyristor.
Important Questions from Types of FET
The transconductance g mof a JFET is equal to:
\(\frac{ I _{ DSS }}{ V _{ P }}\left(1-\frac{ V _{ GS }}{ V _{ P }}\right)\)
The CMOS inverter can be used as an amplifier when:
In JFET, the Pinch‐off Voltage can be defined as:
In JFET, the current density in the x-direction is:
A. σ(x)E x
B. qN DμE x
C. \(\rm \frac{q}{2 \in_s}N_D\mu\)
D. \(\rm \frac{N_D\mu}{2 \in_s}\)
Choose the correct answer from the options given below:
Match List I with List II
List – I
List – II
JFET - Bias
Characteristic Equation
A.
Self - bias
I.
\(\rm I_D = \frac{V_{SS}-V_{GS}}{R_S}\)
B.
Voltage – divider bias
II.
\(\rm I_D = \frac{V_{EE}-V_{BE}}{R_E}\)
C.
Source bias
III.
V GS = -I DR S
D.
Current – source bias
IV.
\(\rm I_D = \frac{V_{G}-V_{GS}}{R_S}\)
Choose the correct answer from the options given below:
