Chapter 12
1. An emitter follower has a voltage gain that is
a. Much less than one
b. Approximately equal to one
c. Greater than one
d. Zero
2. The total ac emitter resistance of an emitter follower equals
a. re'
b. re
c. re + re'
d. RE
3. The input impedance of the base of an emitter follower is usually
a. Low
b. High
c. Shorted to ground
d. Open
4. The dc emitter current for class A emitter followers is
a. The same as the ac emitter current
b. VE divided by RE
c. Vc divided by Rc
d. The same as the load current
5. The ac base voltage of an emitter follower is across the
a. Emitter diode
b. DC emitter resistor
c. Load resistor
d. Emitter diode and external ac emitter resistance
6. The output voltage of an emitter follower is across the
a. Emitter diode
b. DC collector resistor
c. Load resistor
d. Emitter diode and externalac emitter resistance
7. If Beta = 200 and re = 150 ohm, the input impedance of the base is
approximately
a. 30 kohm
b. 600 n
c. 3 kohm
d. 5 kohm
8. The input voltage to an emitter follower is usually
a. Less than the generator voltage
b. Equal to the generator voltage
c. Greater than the generator voltage
d. Equal to the supply voltage
9. The ac emitter current is closest to
a. VG divided by re
b. vin divided by re'
c. VG divided by re'
d. vin divided by re
10. The output voltage of an emitter follower is approximately
a. 0
b. VG
c. vin
d. Vcc
11. The ac load line of an emitter follower is usually
a. The same as the dc load line
b. More horizontal than the dc load line
c. Steeper than the dc load line
d. Vertical
12. If the input voltage to an emitter follower is too large, the output voltage will be
a. Smaller
b. Larger
c. Equal
d. Clipped
13. If the Q point is at the middle of the dc load line, clipping will first occur on the
a. Left voltage swing
b. Upward current swing
c. Positive half cycle of input
d. Negative half cycle of input
14. If an emitter follower has VCEQ = 5 V, ICQ = 1 mA, and re = 1 kohm, the maximum peak-to-peak unclipped output is
a. 1 V
b. 2 V
c. 5 V
d. 10 V
15. If the load resistance of an emitter follower is very large, the external ac
emitter resistance equals
a. Generator resistance
b. Impedance of the base
c. DC emitter resistance
d. DC collector resistance
16. If an emitter follower hasre' = 10 ohm and re = 90 ohm, the voltage gain is approximately
a. 0
b. 0.5
c. 0.9
d. 1
17. A square wave out of an emitter follower implies
a. No clipping
b. Clipping at saturation
c. Clipping at cutoff
d. Clipping on both peaks
18. A Darlington transistor has
a. A very low input impedance
b. Three transistors
c. A very high current gain
d. One VBE drop
19. The ac load line of the emitter follower is
a. The same as the dc load line
b. Different from the dc load line
c. Horizontal
d. Vertical
20. If the generator voltage is 5 mV in an emitter follower, the output voltage across the load is closest to
a. 5 mV
b. 150 mV
c. 0.25 V
d. 0.5 V
21. If the load resistor of Fig. 12-la in your textbook is shorted, which of the following are different from their normal values:
a. Only ac voltages
b. Only dc voltages
c. Both dc and ac voltages
d. Neither dc nor ac voltages
22. If R1 is open in an emitter follower, which of these is true?
a. DC base voltage is Vcc
b. DC collector voltage is zero
c. Output voltage is normal
d. DC base voltage is zero
23. Usually, the distortion in an emitter follower is
a. Very low
b. Very high
c. Large
d. Not acceptable
24. The distortion in an emitter follower is
a. Seldom low
b. Often high
c. Always low
d. High when clipping occurs
25. If a CE stage is direct coupled to an emitter follower, how many coupling capacitors are there between the two stages?
a. 0
b. 1
c. 2
d. 3
26. A Darlington transistor has a Beta of 8000. If RE = 1 kohm and RL = 100 ohm, the input impedance of the base is closest to
a. 8 kohm
b. 80 kohm
c. 800 kohm
d. 8 Mohm
27. The transistors of a class B push-pull emitter follower are biased at or near
a. Cutoff
b. The center ofthe dc load line
c. Saturation
d. The center ofthe ac load line
28. Thermal runaway is
a. Good for transistors
b. Always desirable
c. Useful at times
d. Usually destructive
29. The ac resistance of compensating diodes
a. Must be included
b. Is usually small enough to ignore
c. Compensates for temperature changes
d. Is very high
30. A small quiescent current is necessary with a class B push-pull amplifier to avoid
a. Thermal runaway
b. Destroying the compensating diodes
c. Crossover distortion
d. Excessive current drain
31. The zener current in a zener follower is
a. Equal to the output current
b. Smaller than the output current
c. Larger than the output current
d. Prone to thermal runaway
32. In the two-transistor voltage regulator, the output voltage
a. Is regulated
b. Has much smaller ripple than the input voltage
c. Is larger than the zener voltage
d. All of the above
33. For a class B push-pull emitter follower to work properly, the emitter diodes must
a. Be able to control the quiescent current
b. Have a power rating greater than the output power
c. Have a voltage gain of I
d. Match the compensating diodes
34. The maximum efficiency of a class B push-pull amplifier is
a. 25 percent
b. 50 percent
c. 78.5 percent
d. 100 percent
35. The ac emitter resistance of an emitter follower
a. Equals the dc emitter resistance
b. Is larger than the load resistance
c. Has no effect on MPP
d. Is usually less than the load resistance
Also try:
Malvino Chapter 1
Malvino Chapter 2
Malvino Chapter 3
Malvino Chapter 4
Malvino Chapter 5
Malvino Chapter 6
Malvino Chapter 7
Malvino Chapter 8
Malvino Chapter 9
Malvino Chapter 10
Malvino Chapter 11
Malvino Chapter 13
Malvino Chapter 14
Malvino Chapter 15
Malvino Chapter 16
Malvino Chapter 17
Malvino Chapter 18
Malvino Chapter 19
Malvino Chapter 20
Malvino Chapter 21
Malvino Chapter 22
Malvino Chapter 23
Malvino Chapter 24
No comments:
Post a Comment