EE AND ECE IMPORTANT MCQ-FET ( Field Effect Transistors ) 1

Q1. A JFET has three terminals, namely …………

1. cathode, anode, grid
2. emitter, base, collector
3. source, gate, drain
4. none of the above

Answer : 3

Q2. A JFET is similar in operation to …………. valve

1. diode
2. pentode
3. triode
4. tetrode

Answer : 2

Q3. A JFET is also called …………… transistor

1. unipolar
2. bipolar
3. unijunction
4. none of the above

Answer : 1

Q4. A JFET is a ………… driven device

1. current
2. voltage
3. both current and voltage
4. none of the above

Answer : 2

Q5. The gate of a JFET is ………… biased

1. reverse
2. forward
3. reverse as well as forward
4. none of the above

Answer : 1

Q6. The input impedance of a JFET is …………. that of an ordinary transistor

1. equal to
2. less than
3. more than
4. none of the above

Answer : 3

Q7. In a p-channel JFET, the charge carriers are …………..

1. electrons
2. holes
3. both electrons and holes
4. none of the above

Answer : 2

Q8. When drain voltage equals the pinch-off-voltage, then drain current …………. with the increase in drain voltage

1. decreases
2. increases
3. remains constant
4. none of the above

Answer : 3

Q9. If the reverse bias on the gate of a JFET is increased, then width of the conducting channel …………..

1. is decreased
2. is increased
3. remains the same
4. none of the above

Answer : 1

Q10. A MOSFET has …………… terminals

1. two
2. five
3. four
4. three

Answer : 4

Q11. A MOSFET can be operated with ……………..

1. negative gate voltage only
2. positive gate voltage only
3. positive as well as negative gate voltage
4. none of the above

Answer : 3

Q12. A JFET has ……….. power gain

1. small
2. very high
3. very small
4. none of the above

Answer : 2

Q13. The input control parameter of a JFET is ……………

1. gate voltage
2. source voltage
3. drain voltage
4. gate current

Answer : 1

Q14. A common base configuration of a pnp transistor is analogous to ………… of a JFET

1. common source configuration
2. common drain configuration
3. common gate configuration
4. none of the above

Answer : 3

Q15. A JFET has high input impedance because …………

1. it is made of semiconductor material
2. input is reverse biased
3. of impurity atoms
4. none of the above

Answer : 2

Q16. In a JFET, when drain voltage is equal to pinch-off voltage, the depletion layers ………

1. almost touch each other
2. have large gap
3. have moderate gap
4. none of the above

Answer : 1

Q17. In a JFET, IDSS is known as …………..

1. drain to source current
2. drain to source current with gate shorted
3. drain to source current with gate open
4. none of the above

Answer : 2

Q18. The two important advantages of a JFET are …………..

1. high input impedance and square-law property
2. inexpensive and high output impedance
3. low input impedance and high output impedance
4. none of the above

Answer : 1

Q19. …………. has the lowest noise-level

1. triode
2. ordinary trnsistor
3. tetrode
4. JFET

Answer : 4

Q20. A MOSFET is sometimes called ………. JFET

1. many gate
2. open gate
3. insulated gate
4. shorted gate

Answer : 3

Q21. Which of the following devices has the highest input impedance?

1. JFET
2. MOSFET
3. Crystal diode
4. ordinary transistor

Answer : 2

Q22. A MOSFET uses the electric field of a ………. to control the channel current

1. capacitor
2. battery
3. generator
4. none of the above

Answer : 1

Q23. The pinch-off voltage in a JFET is analogous to ………. voltage in a vacuum tube

1. anode
2. cathode
3. grid cut off
4. none of the above

Answer : 3

Q24. This question will be available soon

Q25. In class A operation, the input circuit of a JFET is ………. biased

1. forward
2. reverse
3. not
4. none of the above

Answer : 2

Q26. If the gate of a JFET is made less negative, the width of the conducting channel……….

1. remains the same
2. is decreased
3. is increased
4. none of the above

Answer : 3

Q27. The pinch-off voltage of a JFET is about ……….

1. 5 V
2. 0.6 V
3. 15 V
4. 25 V

Answer : 1

Q28. The input impedance of a MOSFET is of the order of ………..

1. Ω
2. a few hundred Ω
3. kΩ
4. several MΩ

Answer : 4

Q29. The gate voltage in a JFET at which drain current becomes zero is called ……….. voltage

1. saturation
2. pinch-off
3. active
4. cut-off

Answer : 2

Q30. This question will be available soon

Q31. In a FET, there are ……….. pn junctions at the sides

1. three
2. four
3. five
4. two

Answer : 4

Q32. The transconductance of a JFET ranges from ……………..

1. 100 to 500 mA/V
2. 500 to 1000 mA/V
3. 0.5 to 30 mA/V
4. above 1000 mA/V

Answer : 3

Q33. The source terminal of a JEFT corresponds to ………….. of a vacuum tube

1. plate
2. cathode
3. grid
4. none of the above

Answer : 2

Q34. The output characteristics of a JFET closely resemble the output characteristics of a ………. valve

1. pentode
2. tetrode
3. triode
4. diode

Answer : 1

Q35. If the cross-sectional area of the channel in n-channel JEFT increases, the drain current ……….

1. is increased
2. is decreased
3. remains the same
4. none of the above

Answer : 1

Q36. The channel of a JFET is between the …………….

1. gate and drain
2. drain and source
3. gate and source
4. input and output

Answer : 2

Q37. For VGS = 0 V, the drain current becomes constant when VDS exceeds ………

1. cut off
2. VDD
3. VP
4. o V

Answer : 3

Q38. A certain JFET data sheet gives  VGS(off) = -4 V. The pinch-off voltage Vp is ……..

1. +4 V
2. -4 V
3. dependent on VGS
4. data insufficient

Answer : 1

Q39. The constant-current region of a JFET lies between

1. cut off and saturation
2. cut off and pinch-off
3. o and IDSS
4. pinch-off and breakdown

Answer : 4

Q40. At cut-off, the JFET channel is ……….

1. at its widest point
2. completely closed by the depletion region
3. extremely narrow
4. reverse baised

Answer : 2

Q41. A MOSFET differs from a JFET mainly because ………………

1. of power rating
2. the MOSFET has two gates
3. the JFET has a pn junction
4. none of the above

Answer : 3

Q42. A certain D-MOSFET is biased at VGS = 0 V. Its data sheet specifies IDSS = 20mA and VGS(off)  = -5 V. The value of the drain current is …………

1. 20 mA
2. 0 mA
3. 40 mA
4. 10 mA

Answer : 1

Q43. A n-channel D-MOSFET with a positive VGS is operating in …………

1. the depletion-mode
2. the enhancement-mode
3. cut off
4. saturation

Answer : 2

Q44. A certain p-channel E-MOSFET has VGS(th)  = -2V. If VGS= 0V, the drain current is ……….

1. 0 mA
2. ID(on)
3. maximum
4. IDSS

Answer : 1

Q45. In a common-source JFET amplifier, the output voltage is …………………

1. 180o out of phase with the input
2. in phase with the input
3. 90o out of phase with the input
4. taken at the source

Answer : 1

Q46. In a certain common-source D-MOSFET amplifier, Vds =3.2 V r.m. and Vgs = 280 mV r.m.s. The voltage gain is …………

1. 1
2. 11.4
3. 8.75
4. 3.2

Answer : 2

Q47. In a certain CS JFET amplifier,  RD= 1kΩ , RS= 560 Ω , VDD=10V and gm= 4500 μS. If the source resistor is completely bypassed, the voltage gain is …………

1. 450
2. 45
3. 2.52
4. 4.5

Answer : 4

Q48. A certain common-source JFET has a voltage gain of 10. If the source bypass capacitor is removed, ……………….

1. the voltage gain will increase
2. the transconductance will increase
3. the voltage gain will decrease
4. the Q-point will shift

Answer : 3

Q49. A CS JFET amplifier has a load resistance of 10 kΩ ,  RD= 820Ω . If gm= 5mS and Vin= 500 mV, the output signal voltage is ………..

1. 2.05 V
2. 25 V
3. 0.5 V
4. 1.89 V

Answer : 4

Q50. If load resistance in the above question (Q.49) is removed, the output voltage will …………

1. increase
2. decrease
3. stay the same
4. be zero

Answer : 1

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