MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 59 Mcqs, each offering curated multiple-choice questions to sharpen your Active Filter Circuits knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
What is the maximum efficiency of a class B circuit? |
| A. | 90% |
| B. | 78.5% |
| C. | 50% |
| D. | 25% |
| Answer» C. 50% | |
| 2. |
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 V CC . |
| 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. | |
| 3. |
Determine V B1 . |
| A. | 0 V |
| B. | 0.7 V |
| C. | 9.3 V |
| D. | 10.7 V |
| Answer» E. | |
| 4. |
n MOS and p MOS transistors can be used for class B. |
| A. | True |
| B. | False |
| C. | - |
| D. | - |
| Answer» B. False | |
| 5. |
The class ________ amplifier is biased below cutoff. |
| A. | A |
| B. | AB |
| C. | B |
| D. | C |
| Answer» E. | |
| 6. |
A class ________ amplifier is biased slightly above cutoff and operates in the linear region for slightly more than 180º of the input cycle. |
| A. | A |
| B. | B |
| C. | C |
| D. | AB |
| Answer» E. | |
| 7. |
The maximum efficiency of a transformer-coupled class A amplifier is ________. |
| A. | 25% |
| B. | 50% |
| C. | 78.5% |
| D. | 63.6% |
| Answer» C. 78.5% | |
| 8. |
Calculate the effective resistance seen looking into the primary of a 20:1 transformer connected to an 8- load. |
| A. | 3.2 k |
| B. | 3.0 k |
| C. | 2.8 k |
| D. | 1.8 k |
| Answer» B. 3.0 k | |
| 9. |
The maximum efficiency of a class B amplifier is ________ percent. |
| A. | 50 |
| B. | 25 |
| C. | 70 |
| D. | 79 |
| Answer» E. | |
| 10. |
Refer to this figure. This amplifier is operating as a ________ amplifier. |
| A. | class A |
| B. | class B |
| C. | class AB |
| D. | class C |
| Answer» D. class C | |
| 11. |
You find that this amplifier only shows the negative alternation at the output. The possible trouble might be that |
| A. | C 3 is shorted. |
| B. | BE 1 is open. |
| C. | BE 2 is open. |
| D. | R 1 is open. |
| Answer» C. BE 2 is open. | |
| 12. |
Calculate the efficiency of a class B amplifier for a supply voltage of V CC = 20 V with peak output voltage of V L (p) = 18 V. Assume R L = 16 . |
| A. | 78.54% |
| B. | 75% |
| C. | 70.69% |
| D. | 50% |
| Answer» D. 50% | |
| 13. |
Which of the following is (are) the disadvantage(s) of a class B complementary-symmetry circuit? |
| A. | It needs two separate voltage sources. |
| B. | There is crossover distortion in the output signal. |
| C. | It does not provide exact switching of one transistor off and the other on at the zero-voltage condition. |
| D. | All of the above |
| Answer» E. | |
| 14. |
A class A amplifier with R C = 3.3 k and R E = 1.2 k has a V CC = 20 V. Find I C(sat) . |
| A. | 4.4 mA |
| B. | 6.1 mA |
| C. | 16.7 mA |
| D. | 20 mA |
| Answer» B. 6.1 mA | |
| 15. |
A class A amplifier has a voltage gain of 30 and a current gain of 25. What is the power gain? |
| A. | 30 |
| B. | 25 |
| C. | 1.2 |
| D. | 750 |
| Answer» E. | |
| 16. |
Which of the following transistors has been quite popular as the driver device for class D amplification? |
| A. | BJT |
| B. | FET |
| C. | UJT |
| D. | MOSFET |
| Answer» E. | |
| 17. |
How many transistors must be used in a class B power amplifier to obtain the output for the full cycle of the signal? |
| A. | 0 |
| B. | 1 |
| C. | 2 |
| D. | 3 |
| Answer» D. 3 | |
| 18. |
For BJT power transistors, the collector terminal is always connected to the transistor's case |
| A. | for easy circuit connection. |
| B. | to prevent shorts. |
| C. | because the collector terminal is the critical terminal for heat dissipation. |
| D. | because the collector terminal is located nearest the case. |
| Answer» D. because the collector terminal is located nearest the case. | |
| 19. |
In practice, the efficiency of a capacitively coupled class A amplifier is about ________%. |
| A. | 25 |
| B. | 40 |
| C. | 70 |
| D. | 10 |
| Answer» E. | |
| 20. |
The least efficient amplifier among all classes is |
| A. | class B. |
| B. | class A. |
| C. | class AB. |
| D. | class C. |
| Answer» C. class AB. | |
| 21. |
In a class AB amplifier, if the V BE drops are not matched to the diode drops or if the diodes are not in thermal equilibrium with the transistors, this can result in |
| A. | a current mirror. |
| B. | diode separation. |
| C. | crossover distortion. |
| D. | thermal runaway. |
| Answer» E. | |
| 22. |
Categorize the power efficiency of each class of amplifier, from worst to best. |
| A. | A, B, AB, D |
| B. | A, AB, D, B |
| C. | A, AB, B, D |
| D. | - |
| Answer» D. - | |
| 23. |
Which of the following describe(s) a power amplifier? |
| A. | It can handle large power. |
| B. | It can handle large current. |
| C. | It does not provide much voltage gain. |
| D. | All of the above |
| Answer» E. | |
| 24. |
You have an application for a power amplifier to operate on FM radio frequencies. The most likely choice would be a ________ amplifier. |
| A. | class A |
| B. | class B |
| C. | class C |
| D. | class AB |
| Answer» D. class AB | |
| 25. |
________ amplifiers primarily provide sufficient power to an output load to drive a speaker from a few watts to tens of watts. |
| A. | Small-signal |
| B. | Power |
| C. | None of the above |
| D. | - |
| Answer» C. None of the above | |
| 26. |
Calculate the efficiency of a transformer-coupled class A amplifier for a supply of 15 V and an output of V(p) = 10 V. |
| A. | 25% |
| B. | 33.3% |
| C. | 50% |
| D. | 78.5% |
| Answer» C. 50% | |
| 27. |
Which of the following instruments displays the harmonics of a distorted signal? |
| A. | Digital multimeter |
| B. | Spectrum analyzer |
| C. | Oscilloscope |
| D. | Wave analyzer |
| Answer» C. Oscilloscope | |
| 28. |
A class B amplifier operates in the linear region for |
| A. | slightly more than 180° of the input cycle. |
| B. | 360° of the input cycle. |
| C. | slightly less than 180° of the input cycle. |
| D. | much less than 180° of the input cycle. |
| Answer» D. much less than 180° of the input cycle. | |
| 29. |
You find that there is no output signal. You measure the dc voltage of Q 1 emitter and find it equal to 0 V. The trouble might be |
| A. | D 1 is shorted. |
| B. | D 2 is shorted. |
| C. | R 1 is open. |
| D. | no trouble, everything is normal. |
| Answer» D. no trouble, everything is normal. | |
| 30. |
Which amplifier is commonly used as a frequency multiplier? |
| A. | class A |
| B. | class B |
| C. | class C |
| D. | all of the above |
| Answer» D. all of the above | |
| 31. |
Refer to this figure. The approximate voltages on the base, collector, and emitter, respectively, are |
| A. | 0.7 V, 6.8 V, 0 V. |
| B. | 0 V, 0 V, 0 V. |
| C. | 0.7 V, 15 V, 0 V. |
| D. | 0.7 V, 0 V, 15 V. |
| Answer» D. 0.7 V, 0 V, 15 V. | |
| 32. |
Which type of amplifier uses pulse (digital) signals in its operation? |
| A. | Class A |
| B. | Class B or AB |
| C. | Class C |
| D. | Class D |
| Answer» E. | |
| 33. |
By how much does the output signal vary for a class AB power amplifier? |
| A. | 360º |
| B. | 180º |
| C. | Between 180º and 360º |
| D. | Less than 180º |
| Answer» D. Less than 180º | |
| 34. |
Which of the power amplifiers is not intended primarily for large-signal or power amplification? |
| A. | Class A |
| B. | Class B or AB |
| C. | Class C |
| D. | Class D |
| Answer» D. Class D | |
| 35. |
Quiescent power is the power dissipation of a transistor |
| A. | with no signal input. |
| B. | with no load. |
| C. | under full load. |
| D. | along the dc load line. |
| Answer» B. with no load. | |
| 36. |
Refer to the figure. The maximum efficiency of this amplifier is |
| A. | about 25%. |
| B. | about 78%. |
| C. | about 70%. |
| D. | about 100%. |
| Answer» C. about 70%. | |
| 37. |
Which of the following is (are) power amplifiers? |
| A. | Class A |
| B. | Class B or AB |
| C. | Class C or D |
| D. | All of the above |
| Answer» E. | |
| 38. |
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 | |
| 39. |
Determine what maximum dissipation will be allowed for a 70-W silicon transistor (rated at 25ºC) if derating is required above 25ºC by a derating factor of 0.6 W/ºC at a case temperature of 100º. |
| A. | 25 W |
| B. | 30 W |
| C. | 35 W |
| D. | 40 W |
| Answer» B. 30 W | |
| 40. |
The Q-point is at cutoff for class ________ operation. |
| A. | A |
| B. | B |
| C. | C |
| D. | AB |
| Answer» C. C | |
| 41. |
Which class of amplifier operates in the linear region for only a small part of the input cycle? |
| A. | A |
| B. | B |
| C. | C |
| D. | AB |
| Answer» D. AB | |
| 42. |
You have an oscilloscope across R L and it shows a zero signal voltage. The problem might be that |
| A. | C 3 is open. |
| B. | BE 1 is open. |
| C. | BE 2 is open. |
| D. | R 1 is open. |
| Answer» B. BE 1 is open. | |
| 43. |
What is the maximum efficiency of a class A circuit with a direct or series-fed load connection? |
| A. | 90% |
| B. | 78.5% |
| C. | 50% |
| D. | 25% |
| Answer» E. | |
| 44. |
What is the maximum temperature rating for silicon power transistors? |
| A. | 50º to 80º |
| B. | 100º to 110º |
| C. | 150º to 200º |
| D. | 250º to 300º |
| Answer» D. 250º to 300º | |
| 45. |
In class B operation, at what fraction of V CC should the level of V L (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 | |
| 46. |
Which of the following instruments allows more precise measurement of the harmonic components of a distorted signal? |
| A. | Digital multimeter |
| B. | Spectrum analyzer |
| C. | Oscilloscope |
| D. | Wave analyzer |
| Answer» E. | |
| 47. |
The principal advantage(s) of MOSFETs over BJTs is (are) |
| A. | their biasing networks are simpler. |
| B. | their drive requirements are simpler. |
| C. | they can be connected in parallel for added drive capability. |
| D. | all of the above |
| Answer» E. | |
| 48. |
Class AB operation is ________ operation. |
| A. | similar to class A |
| B. | similar to class B |
| C. | similar to class C |
| D. | None of the above |
| Answer» E. | |
| 49. |
Which type of power amplifier is biased for operation at less than 180º of the cycle? |
| A. | Class A |
| B. | Class B or AB |
| C. | Class C |
| D. | Class D |
| Answer» D. Class D | |
| 50. |
You find that there is an input signal on the base of Q 1 and Q 2 . However, there is no output signal. You then measure the dc voltages on Q 2 and find them to be all 0 V. The possible trouble might be |
| A. | C 3 is shorted. |
| B. | C 1 is open. |
| C. | R L is shorted. |
| D. | V CC is 0 V. |
| Answer» E. | |