MCQOPTIONS
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MCQOPTIONS
This section includes 303 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
For a Common Source (CS) MOSFET amplifier, what is the input capacitance Cin for the following conditions:Cgs = 4pF, Cgd = 1pF, and Av = 5 |
| A. | 10 pF |
| B. | 16 pF |
| C. | 14 pF |
| D. | 12 pF |
| Answer» B. 16 pF | |
| 52. |
Match the following:a) JFETi) \(\frac{{{\mu _n}{C_{ox}}w}}{{2L}}{\left( {{V_{gs}} - {V_{in}}} \right)^2}\)b) MOSFETii) \(\frac{{2{I_{DSS}}}}{{\left| {{V_p}} \right|}}\left( {1 - \frac{{{V_{GS}}}}{{{V_P}}}} \right)\)c) Gunn diodeiii) q(nlμl + nuμn)d) BJTiv) \(\left( {\beta + 1} \right)\frac{{1 + \frac{{{R_B}}}{{{R_E}}}}}{{\frac{{{R_B}}}{{{R_E}}} + \left( {\beta + 1} \right)}}\)Codes: |
| A. | a-i, b-ii, c-iii, d-iv |
| B. | a-ii, b-i, c-iii, d-iv |
| C. | a-iii, b-iv, c-i, d-ii |
| D. | a-iv, b-iii, c-ii, d-i |
| Answer» C. a-iii, b-iv, c-i, d-ii | |
| 53. |
In a FET, which one of the following has the highest input impedance? |
| A. | Common source |
| B. | Common drain |
| C. | Common gate |
| D. | All junctions |
| Answer» C. Common gate | |
| 54. |
Biasing is used in transition amplifiers to1. Stabilize the operating point against temperature variations.2. Place the operating point in the linear region of the characteristics.3. Make α, β and ICO of the transistor independent of temperature variations.4. Reduce distortion and increase dynamic range. |
| A. | 1, 2, 3 and 4 |
| B. | 1, 2 and 4 only |
| C. | 1, 2 and 3 only |
| D. | 2, 3 and 4 only |
| Answer» C. 1, 2 and 3 only | |
| 55. |
A junction FET can be used as a voltage variable resistor |
| A. | at pinch-off condition |
| B. | beyond pinch-off voltage |
| C. | well below pinch-off condition |
| D. | for any value of VDS |
| Answer» D. for any value of VDS | |
| 56. |
In a CE (common emitter) transistor, VCC = 12 V and the zero-signal collector current is 1 mA. Determine the operating point when collector load (RC) is 6 kΩ |
| A. | 6 V, 1 mA |
| B. | 6 V, 2 mA |
| C. | 12 V, 1 mA |
| D. | 12 V, 2 mA |
| Answer» B. 6 V, 2 mA | |
| 57. |
For the given amplifier circuit, find the input cut-off frequency. FET parameters are gm = 4 mA/V, Cgs = 4 pf, rds = 40 kΩ, Cgd = 2 pF. |
| A. | 35.5 MHz |
| B. | 45.5 MHz |
| C. | 90.5 MHz |
| D. | 10.5 MHz |
| Answer» C. 90.5 MHz | |
| 58. |
Consider the following statements regarding a differential amplifier using an FET pair. The differential output offset voltage is due to:1. Mismatch between FET parameters2. Difference between the values of resistors used in the circuit even though they are marked nominally equal3. Variation in the operating voltage of the circuitWhich of the above statements are correct? |
| A. | 1, 2 and 3 |
| B. | 2 and 3 only |
| C. | 1 and 3 only |
| D. | 1 and 2 only |
| Answer» E. | |
| 59. |
An FET is a semiconductor device with the output current controlled, by an electric field and its current is carried predominately by one type of carriers. It is known as |
| A. | junction transistor |
| B. | unipolar transistor |
| C. | MOSFET |
| D. | IGBT |
| Answer» C. MOSFET | |
| 60. |
Let us assume the emitter current of a bipolar transistor is IE. If it’s made 2IE, then what could be the possible effect on the voltage across base-emitter junction? |
| A. | It increases by about 20 mV |
| B. | It doubles |
| C. | Its halves |
| D. | It decreases by about 20 mV |
| Answer» B. It doubles | |
| 61. |
A transistor is operated in common emitter configuration at VC = 2 V such that a change in the base current from 100 μA to 300 μA produces a change in the collector current from 10 mA to 20 mA. The current gain is |
| A. | 25 |
| B. | 50 |
| C. | 75 |
| D. | 100 |
| Answer» C. 75 | |
| 62. |
Equivalent circuit of FET is shown in the figure below,Where rs 100Ω, Cg = 0.1pF and gm = 0.1mho. For load resistance rL = 500Ω the voltage gain at 1 GHz is: |
| A. | 50 |
| B. | 30 |
| C. | 20 |
| D. | 100 |
| Answer» B. 30 | |
| 63. |
In the circuit shown in the figure, the channel length modulation of all transistors is non-zero (λ ≠ 0). Also, all transistors operate in saturation and have negligible body effect. The ac small signal voltage gain (Vo/Vin) of the circuit is |
| A. | \( - {g_{m1}}\left( {{r_{01}}\parallel {r_{02}}\parallel {r_{03}}} \right)\) |
| B. | \( - {g_{m1}}\left( {{r_{01}}||\frac{1}{{{g_{m3}}}}||{r_{03}}} \right)\) |
| C. | \( - {g_{m1}}\left( {{r_{01}}||\left( {\frac{1}{{{g_{m2}}}}||{r_{02}}} \right)||{r_{03}}} \right)\) |
| D. | \( - {g_{m1}}\left( {{r_{01}}||\left( {\frac{1}{{{g_{m2}}}}||{r_{03}}} \right)||{r_{02}}} \right)\) |
| Answer» D. \( - {g_{m1}}\left( {{r_{01}}||\left( {\frac{1}{{{g_{m2}}}}||{r_{03}}} \right)||{r_{02}}} \right)\) | |
| 64. |
In a JFET drain current is maximum when VGS is |
| A. | Zero |
| B. | Negative |
| C. | Positive |
| D. | Equal to Vp |
| Answer» B. Negative | |
| 65. |
Assertion A): A transmission gate is a bidirectional switch.Reason R): A transmission gate consists of two n-channel enhancement mode transistors.Choose the correct answer: |
| A. | Both A) and R) are true and R) is the correct explanation of A) |
| B. | Both A) and R) are true, but R) is not the correct explanation of A) |
| C. | is true, but R) is false |
| D. | is false, but R) is true |
| Answer» D. is false, but R) is true | |
| 66. |
In a power MOSFET, pinch-off occurs when (VDS is the drain to source voltage, VGS is the gate to source voltage VT is the threshold voltage): |
| A. | VDS = VGS - VT |
| B. | VDS ≤ VGS - VT |
| C. | VGS ≤ VT |
| D. | VDS ≥ VGS -VT |
| Answer» B. VDS ≤ VGS - VT | |
| 67. |
An n-channel JFET has IDSS = 1 mA and Vp = - 5V. Its maximum transconductance is |
| A. | 0.1 millimho |
| B. | 0.4 millimho |
| C. | 1.0 millimho |
| D. | 4.0 millimho |
| Answer» C. 1.0 millimho | |
| 68. |
A bipolar transistor is operating in the active region with a collector current of 1 mA. The β of the transistor is 100 and the thermal voltage (VT) is 25 mV. The trans-conductance (gm) and the input resistance (rπ) of the transistor in the common-emitter configuration are, respectively |
| A. | 25 mA/V and 15.625 kΩ |
| B. | 40 mA/V and 4.0 kΩ |
| C. | 25 mA/V and 2.5 kΩ |
| D. | 40 mA\V and 2.5 kΩ |
| Answer» E. | |
| 69. |
In a JFET, the maximum value of transconductance gm is: |
| A. | \(\frac{{{I}_{DSS}}}{\left| {{V}_{p}} \right|}\) |
| B. | \(\frac{2{{I}_{DSS}}}{\left| {{V}_{P}} \right|}\) |
| C. | \(\sqrt{\frac{2{{I}_{DSS}}}{\left| {{V}_{P}} \right|}}\) |
| D. | \(\sqrt{\frac{{{I}_{DSS}}}{\left| {{V}_{P}} \right|}}\) |
| Answer» C. \(\sqrt{\frac{2{{I}_{DSS}}}{\left| {{V}_{P}} \right|}}\) | |
| 70. |
Consider an n-channel MOSFET with parameters:Kn = 0.25 mA/V2 , VTN = 1 V, λ = 0, Cgd = 0.04 pF and Cgs = 0.2 pFIf the transistor is biased at VGS = 3 V, the unity-gain bandwidth of an FET will be |
| A. | 626 MHz |
| B. | 646 MHz |
| C. | 663 MHz |
| D. | 683 MHz |
| Answer» D. 683 MHz | |
| 71. |
Power consumed in a CMOS circuit operating at frequency f is proportional to: |
| A. | Vcc |
| B. | Vcc f |
| C. | \(V_{cc}^2 f\) |
| D. | \(V_{cc}^2 f^2\) |
| Answer» D. \(V_{cc}^2 f^2\) | |
| 72. |
An FET has a gate source bias of -2 V. The ac input signal ± 1.2 V. The class of operation is |
| A. | A |
| B. | B |
| C. | C |
| D. | AB |
| Answer» B. B | |
| 73. |
Output Impedance of a source follower is: |
| A. | 1 / gm + rd |
| B. | rd / (1 + gm.rd) |
| C. | rd |
| D. | None |
| Answer» C. rd | |
| 74. |
In RC inductive reactance, FET is so arranged that |
| A. | Xc > R |
| B. | Xc < R |
| C. | Xc = R |
| D. | Xc = 10 R |
| Answer» C. Xc = R | |
| 75. |
Identify the type of device from the characteristics shown in the following figure.X axis: VD (drain voltage);Y axis: ID (Drain electric current); VG (Gate Voltage) |
| A. | PN diode |
| B. | JFET |
| C. | SCR |
| D. | BJT |
| Answer» C. SCR | |
| 76. |
FET is a ______. |
| A. | Current and voltage controlled device |
| B. | Power controlled device |
| C. | Voltage controlled device |
| D. | Current controlled device |
| Answer» D. Current controlled device | |
| 77. |
A common gate amplifier has |
| A. | high input resistance and high output resistance |
| B. | low input resistance and high output resistance |
| C. | low input resistance and low output resistance |
| D. | high input resistance and low output resistance |
| Answer» C. low input resistance and low output resistance | |
| 78. |
For the n-channel enhancement MOSFET shown in figure, the threshold voltage Vth = 2 V. The drain current ID of the MOSFET is 4 mA when the drain resistance RD is 1 kΩ. If the value of RD is increased to 4 kΩ, drain current ID will become |
| A. | 2.8 mA |
| B. | 2.0 mA |
| C. | 1.4 mA |
| D. | 1.0 mA |
| Answer» D. 1.0 mA | |
| 79. |
For a given JFET, the typical values of amplification factor and transconductance are given as 40 and 100 μs respectively. The dynamic drain resistance of JFET will be: |
| A. | 200 Ω |
| B. | 400 Ω |
| C. | 200 kΩ |
| D. | 400 kΩ |
| Answer» E. | |
| 80. |
Consider an n-channel MOSFET having width W, length L and electron mobility in the channel is μn and capacitance per unit area is Cox. If gate to source voltage VGS = 0.7V, drain to source voltage VDS = 0.2 V, μnCox = 120μA/V, threshold voltage VT = 0.4V and (W/L) = 60. Calculate the trans-conductance gm in mA/V. |
| A. | 2.5mA /V |
| B. | 1.65 mA /V |
| C. | 3mA /V |
| D. | 1.44mA /V |
| Answer» E. | |
| 81. |
A voltage amplifier is constructed using enhancement mode MOSFETs labelled M1, M2, M3 and M4 in the figure below. M1, M2 and M4 are n-channel MOSFETs and M3 is a p-channel MOSFET. All MOSFETs operate in saturation mode and channel length modulation can be ignored. The low frequency, small signal input and output voltages are vin and vout respectively and the dc power supply voltage is VDD. All n-channel MOSFETs have identical transconductance gmn while the p-channel MOSFET has transconductance gmp. The expressions for the low frequency small signal voltage gain Vout/Vin is |
| A. | −gmn/gmp |
| B. | −gmn (gmn + gmp)−1 |
| C. | +gmn/gmp |
| D. | gmn (gmn + gmp)−1 |
| Answer» D. gmn (gmn + gmp)−1 | |
| 82. |
For a reverse gate voltage of 12 V in JFET, the gate current is 1 nA. The resistance between the gate and source is: |
| A. | 12,000 MΩ |
| B. | 12,000 kΩ |
| C. | 16,000 MΩ |
| D. | 18,000 kΩ |
| Answer» B. 12,000 kΩ | |
| 83. |
FET is a ______ controlled device. |
| A. | current |
| B. | resistance |
| C. | impedance |
| D. | voltage |
| Answer» E. | |
| 84. |
In a transconductance, the device output |
| A. | voltage depends upon the input voltage |
| B. | voltage depends upon the input current |
| C. | current depends upon the input voltage |
| D. | current depends upon the input current |
| Answer» D. current depends upon the input current | |
| 85. |
Minimum number of complementary CMOS transistors pair will be required to implement function, \(F = ABC + \overline {\left( {A + B + C} \right)} \) are |
| A. | 6 |
| B. | 7 |
| C. | 8 |
| D. | 9 |
| Answer» E. | |
| 86. |
In a JFET, the drain current is maximum when VGS is |
| A. | Zero |
| B. | Negative |
| C. | Positive |
| D. | Equal to VP |
| Answer» B. Negative | |
| 87. |
The gate of a JFET is ___________ biased |
| A. | reverse |
| B. | forward |
| C. | reverse as well as forward |
| D. | none of the above |
| Answer» B. forward | |
| 88. |
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 ___________ |
| A. | 20 mA |
| B. | 0 mA |
| C. | 40 mA |
| D. | 10 mA |
| Answer» B. 0 mA | |
| 89. |
A certain common source JFET has a voltage gain of 10. If the source bypass capacitor is removed, ___________ |
| A. | the voltage gain will increase |
| B. | the transconductance will increase |
| C. | the voltage gain will decrease |
| D. | the Q-point will shift |
| Answer» D. the Q-point will shift | |
| 90. |
The input impedance of a MOSFET is of the order of ___________ |
| A. | O |
| B. | a few hundred O |
| C. | kΩ |
| D. | several MO |
| Answer» E. | |
| 91. |
In a FET, there are ___________ pn junctions at the sides |
| A. | three |
| B. | four |
| C. | five |
| D. | two |
| Answer» E. | |
| 92. |
The channel of a JFET is between the ___________ |
| A. | gate and drain |
| B. | drain and source |
| C. | gate and source |
| D. | input and output |
| Answer» C. gate and source | |
| 93. |
A JFET is similar in operation to ___________ valve |
| A. | diode |
| B. | pentode |
| C. | triode |
| D. | tetrode |
| Answer» C. triode | |
| 94. |
In a JFET, when drain voltage is equal to pinch-off voltage, the depletion layers |
| A. | almost touch each other |
| B. | have large gap |
| C. | have moderate gap |
| D. | none of the above |
| Answer» B. have large gap | |
| 95. |
A MOSFET can be operated with ___________ |
| A. | negative gate voltage only |
| B. | positive gate voltage only |
| C. | positive as well as negative gate voltage |
| D. | none of the above |
| Answer» D. none of the above | |
| 96. |
In class A operation, the input circuit of a JFET is ___________ biased |
| A. | forward |
| B. | reverse |
| C. | not |
| D. | none of the above |
| Answer» C. not | |
| 97. |
A CS JFET amplifier has a load resistance of 10 kΩ , RD= 820° . If gm= 5mS and Vin= 500 mV, the output signal voltage is ___________ |
| A. | 2.05 V |
| B. | 25 V |
| C. | 0.5 V |
| D. | 1.89 V |
| Answer» E. | |
| 98. |
In a common source JFET amplifier, the output voltage is ___________ |
| A. | in phase with the input |
| B. | taken at the source |
| Answer» B. taken at the source | |
| 99. |
A MOSFET is sometimes called ___________ JFET |
| A. | many gate |
| B. | open gate |
| C. | insulated gate |
| D. | shorted gate |
| Answer» D. shorted gate | |
| 100. |
In a JFET, IDSS is known as ___________ |
| A. | drain to source current |
| B. | drain to source current with gate shorted |
| C. | drain to source current with gate open |
| D. | none of the above |
| Answer» C. drain to source current with gate open | |