MCQOPTIONS
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MCQOPTIONS
This section includes 68 Mcqs, each offering curated multiple-choice questions to sharpen your Linear Integrated Circuit knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A ________ power amplifier is limited to use at one fixed frequency. |
| A. | class A |
| B. | class B or AB |
| C. | class C |
| D. | class D |
| Answer» D. class D | |
| 2. |
A heat sink provides ________ thermal resistance between case and air. |
| A. | a high |
| B. | a low |
| C. | the same |
| D. | None of the above |
| Answer» C. the same | |
| 3. |
The ________ has the hottest temperature in a power transistor. |
| A. | heat sink |
| B. | case |
| C. | junction |
| D. | None of the above |
| Answer» D. None of the above | |
| 4. |
Improvement in production techniques of power transistors have ________. |
| A. | produced higher power ratings in small-sized packaging cases |
| B. | increased the maximum transistor breakdown voltage |
| C. | provided faster-switching power transistors |
| D. | All of the above |
| Answer» E. | |
| 5. |
The greater the power handled by the power transistor, ________ the case temperature. |
| A. | the higher |
| B. | the lower |
| C. | there is no change in |
| D. | None of the above |
| Answer» B. the lower | |
| 6. |
In Fourier technique, any periodic distorted waveform can be represented by ________ the fundamental and all harmonic components. |
| A. | multiplying |
| B. | subtracting |
| C. | dividing |
| D. | adding |
| Answer» E. | |
| 7. |
The complementary Darlington-connected transistor for a class B amplifier provides ________ output current and ________ output resistance. |
| A. | higher, higher |
| B. | higher, lower |
| C. | lower, lower |
| D. | lower, higher |
| Answer» C. lower, lower | |
| 8. |
The fundamental component is typically ________ any harmonic component. |
| A. | larger than |
| B. | the same as |
| C. | smaller than |
| D. | None of the above |
| Answer» B. the same as | |
| 9. |
In class B operation, the current drawn from a single power supply has the form of ________ rectified signal. |
| A. | a full-wave |
| B. | a half-wave |
| C. | both a full-wave and a half-wave |
| D. | None of the above |
| Answer» B. a half-wave | |
| 10. |
In a class A transformer-coupled amplifier, the ________ the value of VCEmax and the ________ the value of VCEmin, the ________ the efficiency to (from) the theoretical limit of 50%. |
| A. | larger, smaller, farther |
| B. | larger, smaller, closer |
| C. | smaller, larger, closer |
| D. | None of the above |
| Answer» C. smaller, larger, closer | |
| 11. |
The highest efficiency is obtained in class B operation when the level of VL(p) is equal to ________. |
| A. | 0.25VCC |
| B. | 0.50VCC |
| C. | VCC |
| D. | 2VCC |
| Answer» D. 2VCC | |
| 12. |
________ transistors can be used to build a class B amplifier. |
| A. | npn and pnp |
| B. | nMOS and pMOS |
| C. | Both npn and pnp or nMOS and pMOS |
| D. | None of the above |
| Answer» D. None of the above | |
| 13. |
A class A amplifier dissipates ________ power when the load is drawing maximum power from the circuit. |
| A. | the least |
| B. | about the same |
| C. | the most |
| D. | None of the above |
| Answer» B. about the same | |
| 14. |
The amount of power dissipated by the transistor is the ________ of that drawn from the dc supply (set by the bias point) and the amount delivered to the ac load. |
| A. | summation |
| B. | product |
| C. | difference |
| D. | average |
| Answer» D. average | |
| 15. |
The slope of the ac load line in the class A transformer-coupled transistor is ________. |
| A. | –1/RL (load resistor) |
| B. | 1/(a2RL) |
| C. | –1/(a2RL) |
| D. | 1/RL |
| Answer» D. 1/RL | |
| 16. |
In a class A transformer-coupled power amplifier, ________ winding resistance of the transformer determine(s) the dc load line for the circuit. |
| A. | the ac |
| B. | the dc |
| C. | both the ac and dc |
| D. | neither the ac nor dc |
| Answer» C. both the ac and dc | |
| 17. |
The reflected impedance seen from one side of the transformer to the other side is ________. |
| A. | N1/N2 |
| B. | (N1/N2)2 |
| C. | (N1/N2)1/3 |
| D. | N1× N2 |
| Answer» C. (N1/N2)1/3 | |
| 18. |
A form of class A amplifier having maximum efficiency of ________ uses a transformer to couple the output signal to the load. |
| A. | 90% |
| B. | 78.5% |
| C. | 50% |
| D. | 25% |
| Answer» D. 25% | |
| 19. |
The beta of a power transistor is generally ________. |
| A. | more than 200 |
| B. | 100 to 200 |
| C. | less than 100 |
| D. | 0 |
| Answer» D. 0 | |
| 20. |
Class D operation can achieve power efficiency of over ________. |
| A. | 90% |
| B. | 78.5% |
| C. | 50% |
| D. | 25% |
| Answer» B. 78.5% | |
| 21. |
________ amplifiers have the highest overall efficiency. |
| A. | Class A |
| B. | Class B or AB |
| C. | Class C |
| D. | Class D |
| Answer» E. | |
| 22. |
In class B power amplifiers, the output signal varies for ________ of the cycle. |
| A. | 360º |
| B. | 180º |
| C. | between 180º and 360º |
| D. | less than 180º |
| Answer» C. between 180º and 360º | |
| 23. |
In ________ power amplifiers, the output signal varies for a full 360º of the cycle. |
| A. | class A |
| B. | class B or AB |
| C. | class C |
| D. | class D |
| Answer» B. class B or AB | |
| 24. |
The main feature(s) of a large-signal amplifier is (are) the ________. |
| A. | circuit's power efficiency |
| B. | maximum amount of power that the circuit is capable of handling |
| C. | impedance matching to the output |
| D. | All of the above |
| Answer» E. | |
| 25. |
Power amplifiers primarily provide sufficient power to an output load, typically from ________ to ________. |
| A. | a few kW, tens of kW |
| B. | 500 W, 1 kW |
| C. | 100 W, 500 W |
| D. | a few W, tens of W |
| Answer» E. | |
| 26. |
A silicon power transistor is operated with a heat sink ( SA = 1.5ºC/W). The transistor, rated at 150 W (25ºC), has JC = 0.5º C/W, and the mounting insulation has CS = 0.6 ºC/W. What is the maximum power that can be dissipated if the ambient temperature is 50ºC and TJmax = 200 ºC? |
| A. | 61.5 W |
| B. | 60.0 W |
| C. | 57.7 W |
| D. | 55.5 W |
| Answer» D. 55.5 W | |
| 27. |
nMOS and pMOS transistors can be used for class B. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 28. |
Calculate the efficiency of a class B amplifier for a supply voltage of VCC = 20 V with peak output voltage of VL(p) = 18 V. Assume RL = 16. |
| A. | 78.54% |
| B. | 75% |
| C. | 70.69% |
| D. | 50% |
| Answer» D. 50% | |
| 29. |
In class B operation, at what fraction of VCC should the level of VL(p) be to achieve the maximum power dissipated by the output transistor? |
| A. | 0.5 |
| B. | 0.636 |
| C. | 0.707 |
| D. | 1 |
| Answer» C. 0.707 | |
| 30. |
What transformer turns ratio is required to match an 8- speaker load so that the effective load resistance seen at the primary is 12.8 k? |
| A. | 20:1 |
| B. | 40:1 |
| C. | 50:1 |
| D. | 60:1 |
| Answer» C. 50:1 | |
| 31. |
A class C amplifier is a linear amplifier. |
| A. | True |
| B. | False |
| Answer» C. | |
| 32. |
Class AB operation always requires a dual (+/–) supply. |
| A. | True |
| B. | False |
| Answer» C. | |
| 33. |
In a class B push-pull amplifier, crossover distortion occurs when both transistors are off and the input signal voltage must exceed VBE before a transistor conducts. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 34. |
Class A amplifiers operate in the active region of the load line all of the time. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 35. |
The efficiency of any amplifier is the ratio of signal output power to signal input power. |
| A. | True |
| B. | False |
| Answer» C. | |
| 36. |
In a large-signal amplifier, the ac signal only needs to move over a small percentage of the total ac load line. |
| A. | True |
| B. | False |
| Answer» C. | |
| 37. |
Class B amplifiers are usually zero-biased. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 38. |
The class C amplifier is biased below cutoff. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 39. |
Class B amplifiers are usually operated in push-pull to obtain an output that is a near replica of the input signal. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 40. |
A class A amplifier conducts 180° of the cycle. |
| A. | True |
| B. | False |
| Answer» C. | |
| 41. |
A class C amplifier has a tank circuit in the output. The amplifier is conducting only 28°. The output voltage is |
| A. | 0 V. |
| B. | a dc value equal to VCC. |
| C. | a sine wave. |
| D. | a square wave with a frequency determined by the tank. |
| Answer» D. a square wave with a frequency determined by the tank. | |
| 42. |
You find that there is an input signal on the base of Q1 and Q2. However, there is no output signal. You then measure the dc voltages on Q2 and find them to be all 0 V. The possible trouble might be |
| A. | C3 is shorted. |
| B. | C1 is open. |
| C. | RL is shorted. |
| D. | VCC is 0 V. |
| Answer» E. | |
| 43. |
You find that there is no output signal. You measure the dc voltage of Q1 emitter and find it equal to 0 V. The trouble might be |
| A. | D1 is shorted. |
| B. | D2 is shorted. |
| C. | R1 is open. |
| D. | no trouble, everything is normal. |
| Answer» D. no trouble, everything is normal. | |
| 44. |
You have an oscilloscope across RL and it shows a zero signal voltage. The problem might be that |
| A. | C3 is open. |
| B. | BE1 is open. |
| C. | BE2 is open. |
| D. | R1 is open. |
| Answer» B. BE1 is open. | |
| 45. |
Calculate VB2. |
| A. | 0 V |
| B. | 0.7 V |
| C. | 9.3 V |
| D. | 10.7 V |
| Answer» D. 10.7 V | |
| 46. |
Determine VB1. |
| A. | 0 V |
| B. | 0.7 V |
| C. | 9.3 V |
| D. | 10.7 V |
| Answer» E. | |
| 47. |
Refer to this figure. The dc voltage on the collector, VC, is |
| A. | 5.4 V. |
| B. | 6.6 V. |
| C. | 12 V. |
| D. | 0 V. |
| Answer» B. 6.6 V. | |
| 48. |
A class A amplifier with RC = 3.3 k and RE = 1.2 k has a VCC = 20 V. Find IC(sat). |
| A. | 4.4 mA |
| B. | 6.1 mA |
| C. | 16.7 mA |
| D. | 20 mA |
| Answer» B. 6.1 mA | |
| 49. |
If the output power of an amplifier is 10 V, and the input power supplied to the amplifier is 0.229 V given that the DC voltage used is 38.5 V, efficiency of the power amplifier is: |
| A. | 25% |
| B. | 50% |
| C. | 75% |
| D. | 35% |
| Answer» B. 50% | |
| 50. |
_______________ are used in the final stages of radar and radio transmitters to increase the radiated power level. |
| A. | Power amplifiers |
| B. | Oscillators |
| C. | Transistors |
| D. | Attenuators |
| Answer» B. Oscillators | |