Tue. Nov 11th, 2025

Unit 5 – FET, MOSFET & UJT

English – Part B (2-mark) Short Answer Questions and Answers

  1. What is pinch-off voltage in JFET?
    Drain voltage where channel current becomes constant.
  2. Two advantages of FET over BJT.
    High input impedance, low noise, low power consumption.
  3. Define MOSFET.
    Metal-Oxide-Semiconductor FET with insulated gate and very high input impedance.
  4. Define FET.
    Voltage-controlled unipolar device that controls current through channel by electric field.
  5. What are drain characteristics?
    Plots of ID vs VDS for various VGS values.
  6. What is intrinsic stand-off ratio (η)?
    η = RB1 / (RB1 + RB2); ratio of UJT standoff voltage to supply voltage (≈ 0.5–0.8).
  7. Output waveform of UJT relaxation oscillator.
    Saw-tooth wave across capacitor.
  8. Name three terminals of UJT.
    Emitter (E), Base 1 (B1), Base 2 (B2).
  9. Name three terminals of JFET and applications.
    Gate, Source, Drain; used in mixers, buffers, oscillators.
  10. Difference between enhancement and depletion MOSFET.
    Enhancement type normally OFF (channel induced); depletion type normally ON (channel exists at VGS = 0).

Tamil – Part B (2-mark) Short Answer Questions and Answers

  1. What is pinch-off voltage in JFET?
    Drain current constant ஆகும் voltage pinch-off voltage ஆகும்.
  2. Two advantages of FET over BJT.
    High input impedance, low noise, less power loss.
  3. Define MOSFET.
    Metal-Oxide-Semiconductor FET ; Gate insulated ஆக இருக்கும் – high input impedance device.
  4. Define FET.
    Voltage controlled unipolar device ; channel current electric field மூலம் control ஆகும்.
  5. What are drain characteristics?
    ID vs VDS plots for different VGS values.
  6. Define intrinsic stand-off ratio (η).
    η = RB1 / (RB1 + RB2); UJT இன் standoff voltage ratio (0.5 to 0.8).
  7. Output waveform of UJT relaxation oscillator.
    Capacitor இல் saw-tooth waveform உருவாகும்.
  8. Name three terminals of UJT.
    Emitter (E), Base1 (B1), Base2 (B2).
  9. Name three terminals of JFET and applications.
    Gate, Source, Drain – Mixers, Buffers, Oscillator circuits இல் use செய்கிறது.
  10. Difference between Enhancement and Depletion MOSFET.
    Enhancement MOSFET normally OFF; channel create வேண்டும்.
    Depletion MOSFET normally ON; channel already present.