Field-Effect Transistors (FET) MCQ (Part-2)

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Field-Effect Transistors (FET) MCQ

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Field-Effect Transistors (FET) MCQ (Part-1)

Multiple-Choice Questions

Q.1. If the gate of a JFET is made less negative, the width of the conducting channel …….

  • remains the same
  • is decreased
  • is increased
  • none of the above

Answer: is increased

Q.2. The pinch-off voltage of a JFET is about …….

  • 5 V
  • 0.6 V
  • 15 V
  • 25 V

Answer: 5 V

Q.3. The input impedance of a MOSFET is of the order of …………..

  • Ω
  • a few hundred Ω
  • k Ω
  • several M Ω

Answer: several M Ω

Q.4. The gate voltage in a JFET at which drain current becomes zero is called ………….. voltage.

  • saturation
  • pinch-off
  • active
  • cut-off

Answer: pinch-off

Q.5. The drain current ID in a JFET is given by …………..

  • I_{D}=I_{DSS}\left ( 1-\frac{V_{GS}}{V_{P}} \right )^{2}
  • I_{D}=I_{DSS}\left ( 1+\frac{V_{GS}}{V_{P}} \right )^{2}
  • I_{D}=I_{DSS}\left ( 1-\frac{V_{P}}{V_{GS}} \right )^{2}
  • I_{D}=I_{DSS}\left ( 1+\frac{V_{P}}{V_{GS}} \right )^{2}

Answer: I_{D}=I_{DSS}\left ( 1-\frac{V_{GS}}{V_{P}} \right )^{2}

Q.6. In a FET, there are …………… pn junctions at the sides.

  • three
  • four
  • five
  • two

Answer: two

Q.7. The transconductance of a JFET ranges from ……………

  • 100 to 500 mA/V
  • 500 to 1000 mA/V
  • 0.5 to 30 mA/V
  • above 1000 mA/V

Answer: 0.5 to 30 mA/V

Q.8. The source terminal of a JFET corresponds to …………… of a vacuum tube.

  • plate
  • cathode
  • grid
  • none of the above

Answer: grid

Q.9. The output characteristics of a JFET closely resemble the output characteristics of a …………… valve.

  • pentode
  • tetrode
  • triode
  • diode

Answer: pentode

Q.10. If the cross-sectional area of the channel in n-channel JFET increases, the drain current ……………

  • is increased
  • is decreased
  • remains the same
  • none of the above

Answer: is increased

Q.11. The channel of a JFET is between the ……………

  • gate and drain
  • drain and source
  • gate and source
  • input and output

Answer: drain and source

Q.12. For VGS= 0 V, the drain current becomes constant when VDS exceeds ……………

  • cut off
  • VDD
  • VP
  • 0 V

Answer: VP

Q.13. A certain JFET datasheet gives VGS(off) = − 4 V. The pinch-off voltage VP is ………….

  • + 4 V
  • − 4 V
  • dependent on VGS
  • data insufficient

Answer: + 4 V

Q.14. The constant-current region of a JFET lies between ……………

  • cut off and saturation
  • cut off and pinch-off
  • 0 and IDSS
  • pinch-off and breakdown

Answer: pinch-off and breakdown

Q.15. At cut-off, the JFET channel is ……………

  • at its widest point
  • completely closed by the depletion region
  • extremely narrow
  • reverse biased

Answer: completely closed by the depletion region

Q.16. A MOSFET differs from a JFET mainly because ……………

  • of power rating
  • the MOSFET has two gates
  • the JFET has a pn junction
  • none of above

Answer: the JFET has a pn junction

Q.17. A certain D-MOSFET is biased at VGS = 0V. Its data sheet specifies IDSS = 20 mA and VGS (off) = – 5V. The value of the drain current is ……………

  • 20 mA
  • 0 mA
  • 40 mA
  • 10 mA

Answer: 20 mA

Q.18. An n-channel D-MOSFET with a positive VGS is operating in ……………

  • the depletion-mode
  • the enhancement-mode
  • cut off
  • saturation

Answer: the enhancement-mode

Q.19. A certain p-channel E-MOSFET has a VGS (th) = – 2V. If VGS = 0V, the drain current is ………

  • 0 mA
  • ID (on)
  • maximum
  • IDSS

Answer: 0 mA

Q.20. In a common-source JFET amplifier, the output voltage is ……………

  • 180° out of phase with the input
  • in phase with the input
  • 90° out of phase with the input
  • taken at the source

Answer: 180° out of phase with the input

Q.21. In a certain common-source D-MOSFET amplifier, Vds = 3.2 V r.m.s. and Vgs = 280 mV r.m.s. The voltage gain is ……………

  • 1
  • 11.4
  • 8.75
  • 3.2

Answer: 11.4

Q.22. In a certain CS JFET amplifier, RD = 1 kΩ, RS = 560Ω, VDD = 10 V and gm = 4500 μS. If the source resistor is completely bypassed, the voltage gain is ……………

  • 450
  • 45
  • 2.52
  • 4.5

Answer: 4.5

Q.23. A certain common-source JFET has a voltage gain of 10. If the source bypass capacitor is removed, ………………….

  • the voltage gain will increase
  • the transconductance will increase
  • the voltage gain will decrease
  • the Q-point will shift

Answer: the voltage gain will decrease

Q.24. A CS JFET amplifier has a load resistance of 10 kΩ and RD = 820Ω. If gm = 5 mS and Vin = 500 mV, the output signal voltage is …

  • 2.05 V
  • 25 V
  • 0.5 V
  • 1.89 V

Answer: 1.89 V

Q.25. If load resistance in Q.49 is removed, the output voltage will ……………

  • increase
  • decrease
  • stay the same
  • be zero

Answer: increase

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