On this page, we will review the Analog Electronics Short Notes PDF Part 27. 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 27
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 are the advantages of JFET?
- High input impedance – Ideal for buffer and amplifier stages.
- Low noise – Suitable for audio and RF applications.
- Voltage-controlled – Easier to use in circuits than current-controlled devices like BJTs.
- Thermal stability – Less sensitive to temperature variations.
- Simple biasing – Requires less complex circuit arrangements.
2. What are the advantages of MOSFET?
- Very high input impedance – Practically infinite due to the insulated gate.
- Low power consumption – Ideal for battery-operated devices.
- High switching speed – Widely used in digital circuits.
- Compact size – Used in ICs and integrated systems.
- Stable operation – Especially in enhancement-mode configurations.
3. What is AC Drain Resistance?
AC drain resistance (rd) is the dynamic resistance offered by the JFET or MOSFET to alternating current flowing from drain to source, while gate-source voltage is kept constant.
Mathematically:
rd = ΔVDS / ΔID (at constant VGS)
4. What is Transconductance?
Transconductance (gm) is the rate of change of drain current (ID) with respect to gate-source voltage (VGS).
It indicates how effectively the input voltage controls the output current.
Formula:
gm = ΔID / ΔVGS
5. What is Amplification Factor?
The amplification factor (μ) of a JFET is the product of AC drain resistance (rd) and transconductance (gm).
Formula:
μ = gm × rd
It tells how much voltage gain the device can provide.
6. What is JFET Biasing?
JFET biasing is the method of setting a proper operating point (Q-point) for the transistor to work efficiently in the active region. It ensures the JFET is properly turned on and avoids distortion or cut-off.
7. What are the types of JFET Biasing?
- Self-bias – Uses a resistor between source and ground.
- Voltage-divider bias – Uses a voltage divider network for setting gate voltage.
- Source bias – Combines gate resistor and source resistor to stabilize Q-point.
8. What are the types of connection in JFET?
- Common Source (CS) – Provides voltage and power gain.
- Common Gate (CG) – Low input impedance, high frequency applications.
- Common Drain (CD) or Source Follower – Used as a buffer, high input, low output impedance.
9. What is D MOSFET?
D-MOSFET stands for Depletion-mode MOSFET.
- It conducts even when VGS = 0.
- Applying negative VGS (N-channel) reduces current, and positive VGS increases it.
- It can operate in both depletion and enhancement mode.
10. What is E MOSFET?
E-MOSFET stands for Enhancement-mode MOSFET.
- It does not conduct when VGS = 0.
- It requires a positive VGS (N-channel) to turn ON.
- It works only in enhancement mode, ideal for digital switches.