On this page, we will review the Analog Electronics Short Notes PDF Part 26. Welcome to Poly Notes Hub, a leading destination for analog electronics notes for engineering students.
Author Name: Arun Paul
Analog Electronics Short Notes Pdf Part 26
Here we have listed some analog electronics short notes for all types of exams like diploma engineering, degree engineering, and GATE exam and many more. In every page, we have listed 10 short analog electronics questions and answers and anyone can download it by a single click for future use.
1. What is the JFET Operation?
The JFET (Junction Field Effect Transistor) operates by controlling the flow of current from the source to drain using a voltage applied at the gate.
- When no gate voltage is applied, the channel between source and drain is fully open, and maximum current flows.
- As a negative voltage is applied to the gate (for N-channel), it narrows the channel, reducing current flow.
- If the gate voltage is made more negative, it can completely block current – this is known as cutoff.
2. What is the MOSFET Operation?
The MOSFET operates similarly, but with a key difference – it has an insulating oxide layer between the gate and the channel.
- When a voltage is applied at the gate, it creates an electric field that attracts or repels carriers in the channel.
- In N-channel MOSFET, applying a positive gate voltage forms a conductive channel, allowing current to flow.
- In P-channel MOSFET, a negative gate voltage allows conduction.
3. What is the Importance of JFET?
The JFET is important because:
- It offers high input impedance, drawing very little current from the input.
- It is less noisy than bipolar transistors, making it suitable for low-noise amplifiers.
- It works as a voltage-controlled device, simplifying circuit design.
4. What is Unipolar Transistor?
A Unipolar Transistor is a type of transistor in which current conduction happens by only one type of charge carrier – either electrons or holes.
JFET and MOSFET are unipolar, because:
- N-channel uses electrons only.
- P-channel uses holes only.
5. Why JFET is Called Unipolar Transistor?
JFET is called a unipolar transistor because only one type of carrier (either electrons or holes) is responsible for the current flow, unlike bipolar junction transistors (BJTs) which use both.
6. How JFET Works as an Amplifier?
In amplifier circuits:
- A small change in gate voltage (input signal) causes a large change in drain current.
- This change in current flows through a load resistor, converting it to an amplified voltage.
- Since JFET has high input impedance, it does not load the previous stage.
7. What are the Features of JFET?
Key features include:
- High input impedance
- Low noise
- Voltage-controlled operation
- Simple biasing
- Low power consumption
- Unipolar device
8. What is Shorted Gate Drain Current (IDSS)?
IDSS is the maximum current that flows from drain to source when the gate is shorted to the source (i.e., gate-source voltage VGS = 0).
It is the saturation current in JFET.
9. What is Pinch-Off Voltage (VP)?
Pinch-off voltage (VP) is the gate-source voltage at which the channel is completely closed, and the drain current becomes constant (saturated). Beyond this point, increasing drain-source voltage does not increase current.
10. What is Gate Source Cut-Off Voltage (VGS(off))?
Gate-Source Cutoff Voltage (VGS(off)) is the negative gate voltage (for N-channel JFET) at which the drain current becomes zero.
It is the point where the JFET turns off completely.