Electronic Devices-Power Amplifiers
Electronic Devices-Power Amplifiers
11. What is the maximum temperature rating for silicon power transistors?
- 50º to 80º
- 100º to 110º
- 150º to 200º
- 250º to 300º
12. What is the maximum efficiency of a class A circuit with a direct or series-fed load connection?
- 90%
- 78.5%
- 50%
- 25%
13. Which class of amplifier operates in the linear region for only a small part of the input cycle?
- A
- B
- C
- AB
15. 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.
- 25 W
- 30 W
- 35 W
- 40 W
16. How many transistors must be used in a class B power amplifier to obtain the output for the full cycle of the signal?
- 0
- 1
- 2
- 3
17. 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?
- 20:1
- 40:1
- 50:1
- 60:1
18. Which of the following is (are) power amplifiers?
- Class A
- Class B or AB
- Class C or D
- All of the above
19. Quiescent power is the power dissipation of a transistor
- with no signal input.
- with no load.
- under full load.
- along the dc load line.
20. Which of the power amplifiers is not intended primarily for large-signal or power amplification?
- Class A
- Class B or AB
- Class C
- Class D