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