Questions on JFET: 1) Which of the following component is a unipolar device?

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1 Questions on JFET: 1) Which of the following component is a unipolar device? a) BJT b) FET c) DJT d) EFT 2) Current Conduction in FET takes place due e) Majority charge carriers only f) Minority charge carriers only g) Both majority as well as minority carriers h) None of the above. 3) FET is a controlled device. i) Voltage j) Current k) Temperature l) All of the above 4) FET stands for m) Field effect transformer n) Full effect transistor o) Field energy transfer p) Field effect transistor 5) FET s are classified as a) BJT and MOSFET b) UJT and BJT c) JFET and MOSFET 6) MOSFET s are classified as a) Depletion MOSFET b) Enhancement MOSFET c) Both a & b d) None 7) MOSFET stands for a) Manganese oxide semiconductor field effect transistor b) Metal oxide semi layer field effect transistor c) Metal oxide semiconductor field effect transistor d) Metal oxide semiconductor field effect transformer Eduspace.co.in 1

2 8) JFET has the following 3 terminals a) Source, base, collector b) Emitter, base, drain c) Source, Drain, Gate d) None of the above 9) In N channel JFET is heavily doped. a) P type region b) N type region c) PN type region d) None 10) The DC supply given to drain is referred to as a. V DD b. V DS c. V GS d. None 11) The symbol for N channel JFET is a) c) b) d) 12) The value of V GS at which drain current I D reduces to zero is called a. Pinch off voltage b. Gate cut- off voltage c. Cut in voltage d. None 13) The value of drain to source voltage V DS at which drain current I D becomes essentially constant is called a. Pinch off voltage b. Gate cut- off voltage c. Cut in voltage d. None 14) The maximum value of drain current I D at gate to source voltage V GS is zero is known as : a. Short circuit drain current b. Open circuit drain current c. Short circuit source current d. Open circuit gate current 15) The input impedance of JFET is Eduspace.co.in 2

3 a. Very low b. Very high c. Keeps changing d. None 16) DMOSFET is the abbreviation for a) Drain MOSFET b) Dynamic MOSFET c) Deflection MOSFET d) Depletion MOSFET 17) In Ohmic region the drain current ( I D ) varies linearly with a. Gate current I G b. Gate to source voltage ( V GS ) c. Drain to source voltage ( V DS ) d. None of the above. 18) The Drain characteristics of JFET is divided into following 3 regions a. Ohmic, Saturation, Breakdown b. Active, Saturation, cut-off c. Ohmic, Active, Breakdown d. All of the above. 19) EMOSFET is the abbreviation for a) Energetic type MOSFET b) Enhancement type MOSFET c) Enable type MOSFET d) None. 20) Gate terminal is called the terminal because reverse bias at gate to source terminal controls the drain current. a. Control b. Compensation c. None d. Both a & b 21) Which terminal represents the control input of a FET? a) Source b) Gate c) Drain d) Base 22) What symbol is used to represent the supply voltage of the supply line that is connected (directly or indirectly) to the drain of a FET? a) V DD b) V SS c) V GS d)v DS Eduspace.co.in 3

4 23) What form of FET is shown here? a) A p-channel JFET. b) An n-channel MOSFET. c) An n-channel JFET. d) A p-channel MOSFET 24) In the FET output characteristics shown below, what region is represented by the symbol 'X' a) Space Charge region b) Saturation region c) ohmic region d) operating region 25) Which of the following statements is incorrect? a) The operation of FETs is essentially non-linear b) The transconductance of a FET is given by g m = I D /V GS. c) In circuits using n-channel FETs the supply voltage is normally more positive than the source. d) All FETs have very high input resistance. 26) Determine the cut-off frequency of the following circuit. Eduspace.co.in 4

5 a)0.63 Hz b) 1.6 Hz c) 3.6 Hz d) 10 Hz 27) FETs may be used as both analogue and logical switches. a) True b)false 28) When implementing integrated circuits, FETs take up much more space than resistors, so we try to use resistors wherever possible. a) True b)false 29) What form of FET is shown here? a) A p-channel JFET. b) An n-channel MOSFET. c) An n-channel JFET. d) A p-channel MOSFET. 30) FET amplifiers provide a) excellent voltage gain Eduspace.co.in 5

6 b) high input impedance c) low power consumption 31) The E-MOSFET is quite popular in applications. a) digital circuitry b) high-frequency c) buffering 32) What is the range of g m for JFETs? a) 1 µs to 10 µs b) 100 µs to 1000 µs c) 1000 µs to 5000 µs d) µs to µs 33) What is the typical value for the input impedance Z i for JFETs? a) 100 k b) 1 M c) 10 M d) 1000 M 34) The steeper the slope of the I D versus V GS curve, the the level of g m. a) less b) Same c) Greater d) None 35) If I D = I DSS / 2, g m = g mo a) 1 b) c) 0.5 d) None 36) Where do you get the level of gm and rd for an FET transistor? a) From the dc biasing arrangement b) From the specification sheet c) From the characteristics 37) Which of the following is (are) related to depletion-type MOSFETs? a) can be negative, zero, or positive b) gm can be greater or smaller than gm0. c) ID can be larger than IDSS. 38) For an FET small-signal amplifier, one could go about troubleshooting a circuit by Eduspace.co.in 6

a) viewing the circuit board for poor solder joints b) using a dc meter c) applying a test ac signal 39) Referring to the transfer characteristics shown below, calculate g m at V GSQ = 1 V.

7 a) viewing the circuit board for poor solder joints b) using a dc meter c) applying a test ac signal 39) Referring to the transfer characteristics shown below, calculate g m at V GSQ = 1 V. a) 2 ms b) 3 ms c) 4 ms d) 5 ms 40 ) The E-MOSFET is quite popular in applications. a) digital circuitry b)high-frequency c)buffering d)all of the above 41. A FET can be used as a variable a) Inductor b) Capacitor c) Resistor d) Voltage source 42. In FET the drain voltage above which there is no increase in the drain current is Called a) Pick off b) Pinch off c) Breakdown d) Critical 43. When the positive voltage on the gate of a P channel JFET is increased, the drain Current will a) Increase b) Decrease c) Remain same d) Any of the above 44. The operation of a JFET involves a flow of a) Minority carriers b) Majority carriers c) Recombination carriers d) none Eduspace.co.in 7

8 45. SCR is a) Three layer two terminal device b) Three layer three terminal device c) Four layer two terminal device d) Four layer three terminal device 46. A Traic is a switch a) Unidirectional b) Bi- directional c) Either if the above d) None 47. In a JFET is usually the point of reference. a) Gate b) Drain c) Source d) Either (b) or (c) 48. A Diac is switch. a) An A.C b) D.C. c) Either if the above d) None 49. The normal way to turn on the diac is by a) Gate current b) Break over voltage c) Either if the above d) None 50. The daic is equivalent to a a) Traic with two gate b) Diode and two resistors c) Pair of SCR s d) Pair of four layer SCR s 51. is the best electronic device for fast switching. a) MOSFET b) JFET c) BJT d) Triode 52. Which semiconductor acts like a NPN and PNP transistors connected base to base and emitter and collector. a) SCR b) UJT c) Diac d) Traic 53. Which semiconductor device behaves like two SCR s a) MOSFET b) JFET c) UJT d) Triac 54. The main factor which differentiates a D-MOSFET and E-MOSFET is the absence a) P-N Junction b) Insulated gate c) Electrons d) Channel 55. The input gate current of a FET is a) A few amperes b) A few milli amperes. c) A few nano amperes d) none 56. A JFET is similar in operation to valve. a) Diode b)pentode c) Triode d) Tetrode. 57. The gate of a JFET biased a) Reversed b) Forward c) Reverse as well as forward d)none Eduspace.co.in 8

9 58) The input impedence of a JFET is that of a ordinary transistor a) Equal to b) Less than c) More than d)none 59)When the drain voltage equals the pinch off voltage then drain current with the increase in drain voltage a) Increases b) Decreases c) Remains constant d)none 60) If the reverse bias on the gate of JFET is increased then the width of conducting channel is a)is Increased b)is decreased c) Remains constant d)none 61) A MOSFET has terminal a) One b) Two c) three d)four 62) A MOSFET can be operated with a) Negative gate voltage only b) Positive gate voltage only c) Negative gate voltage as well as Positive only d)none 63) JFET has power gain a) small b) very high c) very small d)none 64) The input control parameter of a JFET is a) Gate voltage b) Source voltage c) Drain voltage d)gate current 65) A common base configuration of a PNP transistor it analogous to of a JFET a) CS configuration b) CG configuration c) CD configuration d)none 66) In JFET when drain voltage is equal to pinchoff voltage depletion layer a) almost touch each other b) Have large gap c) Have moderate gap d) None 67) In a JFET IDSS is known as a) drain to source current b) drain to source voltage with gate shorted c) drain to source voltage with gate open d) None of the above 68) Two important advantage of a JFET are Eduspace.co.in 9

10 a) High i/p impedence and square law property b) Inexpensive and high o/p impedence. c) Low i/p impedence and high o/p impedence d) None 69) has the lowest noise level a) Triode b) ordinary transistor c) Tertrode d) JFET 70) MOSFET is sometimes called JFET a) Many gate b) open gate c) insulated gate d) shorted gate 71) A MOSFET uses electric field of a to control the channel current. a) capacitor b) Battery c) Generator d) None 72) Pinch off voltage in JFET is analogous to Voltage in vacuum tube a) anode b) cathode c) grid cut off d) none 73) The pinch off voltage of a JFET is about a) 5 V b) 0.6V c) 15 V d) 20 V 74) For VGS = 0 V drain current becomes constant, when VDS exceeds a) Cut off b) VDD c) Vp d) 0 V 75) An SCR is made up of a) Ge b) Si c) carbon d) None 76) An SCR is turned off by a) Reducing anode voltage to 0 b) Reducing gate voltage to 0 c) reverse biasing the gate d) None 77) An SCR is a triggered device a) Voltage b) Current c) Voltage as well as current d) None 78) An SCR is made up of Si and not Ge because Si a) Inexpensive b) Mechanically strong c) Has small leakage current d) Is tetravalent Eduspace.co.in 10

11 79) A Diac is a switch a) An AC b) DC c) A mechanical d) None 80) The device that exhibit negative resistance is a) DIAC b)triac c)transistor d)ujt 81) A DIAC is simply a) A single junction device b) A three junction device c) A TRIAC without gate terminal d) None 82) Power electronics essentially deals with control of a.c. power at a) frequencies above 20 khz b) frequencies above 1000 khz c) frequencies less than 10 hz d) 50 hz frequency 83)Which one of the following is not a characteristic of UJT? a) Intrinsic stand off ratio b)negative resistance c)peak point voltage d)bilateral conduction 84) When temperature increases, the intrinsic stand off ratio a) Increases b) Decreases c) Essentially remains same d) none 85) The triac is like a a) a bidirectional SCR b) a four terminal device c) not a thyristor d) a & b Eduspace.co.in 11

Unit III FET and its Applications. 2 Marks Questions and Answers

Unit III FET and its Applications 2 Marks Questions and Answers 1. Why do you call FET as field effect transistor? The name field effect is derived from the fact that the current is controlled by an electric