Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1)
Which of the following is an advantage of using dB representations of gain values?
1)
A)
Using db values, we can represent large gain values with relatively small numbers.
B)
In multistage amplifiers, gain calculations are simplified by the use of dB values.
C)
Positive and negative dB values represent gain and loss values that are reciprocals of each
other.
D)
All of the above
Answer:
D
A)
B)
C)
D)
2)
An amplifier delivers 500 W to a 600 load. What is the gain in dBm?
2)
A)
53.98 dBm
B)
56.99 dBm
C)
26.99 dBm
D)
Cannot be determined from the information given
Answer:
B
A)
B)
C)
D)
3)
Which network tends to determine the upper cutoff frequency of a FET amplifier?
3)
A)
neither
B)
the output
C)
the input
D)
both
Answer:
C
A)
B)
C)
D)
4)
An amplifier has a midband power gain of 24,500. What is the value of the power gain in dB for the
circuit?
4)
A)
43.9 dB
B)
87.78 dB
C)
4.39 dB
D)
None of the above
Answer:
A
A)
B)
C)
D)
1
5)
The BJT gain–bandwidth product (fT) is ________.
5)
A)
not related to DC bias conditions
B)
inversely related to ( Cbe +Cbc)
C)
inversely related to re
D)
All of the above
Answer:
D
A)
B)
C)
D)
6)
A 3–dB drop in occurs at ________.
6)
A)
fLs and fLo
B)
GdB
C)
f
D)
fHi
Answer:
C
A)
B)
C)
D)
7)
Ri is calcualted as
7)
A)
RS+R1R2re
B)
RS+R1R2(RE + 1)
C)
RS +R1R2RE
D)
None of the above
Answer:
A
A)
B)
C)
D)
8)
Which of the following are properties of logarithms’?
8)
A)
logn(a/b) =logna +lognb
B)
logn1 = 0
C)
logn(1/b) =lognb
D)
None of the above
Answer:
B
A)
B)
C)
D)
2
9)
What is the proper equation for calculating the low frequency break point due to the capacitor CS
for this BJT amplifier?
9)
A)
fLs =1
2RS+R1+R2CS
B)
fLs =1
2RS+RiCS
C)
fLs =1
2RSRiCS
D)
fLs =1
2RS+R1R2CS
Answer:
B
A)
B)
C)
D)
10)
In order to double the sound level perceived by a human ear, the power of the acoustical source
must be increased by a factor of ________.
10)
A)
10
B)
3 dB
C)
2
D)
4
Answer:
A
A)
B)
C)
D)
11)
The BJT gain–bandwidth product is approximately ________.
11)
A)
mid
B)
mid [1–]
C)
mid
D)
None of the above
Answer:
B
A)
B)
C)
D)
3
12)
Which one of the following equations provides the Miller effect input capacitance for a BJT
amplifier?
12)
A)
1 –Av Cf
B)
1 –1
Av Cf
C)
1
1 –Av Cf
D)
1
2RThiCi
Answer:
A
A)
B)
C)
D)
13)
What frequency lies four octaves above 1 kHz?
13)
A)
8 kHz
B)
9 kHz
C)
16 kHz
D)
None of the above
Answer:
C
A)
B)
C)
D)
14)
What frequency is two decades above 5 kHz?
14)
A)
25 kHz
B)
500 kHz
C)
105 kllz
D)
Cannot be determined from the information given
Answer:
B
A)
B)
C)
D)
15)
Which one of the following equations provides the Miller effect output capacitance for a BJT
amplifier?
15)
A)
1
2RThiCi
B)
1 –Av Cf
C)
1
1 –Av Cf
D)
1 –1
Av Cf
Answer:
D
A)
B)
C)
D)
16)
An amplifier has a GBP value of 150 MHz at 600 kHz. At 200 kHz its gain will be ________.
16)
A)
200
B)
3
C)
750
D)
150
Answer:
C
A)
B)
C)
D)
4
17)
An amplifier has values of Pin = 20 mW and Pout = 60 W. What is the value of the power gain in dB
for the circuit?
17)
A)
34.8 dB
B)
69.5 dB
C)
3000 dB
D)
None of the above
Answer:
A
A)
B)
C)
D)
18)
The base–10 logarithm of 1780.331 ________.
18)
A)
33.5
B)
0.335
C)
3.2505
D)
None of the above
Answer:
C
A)
B)
C)
D)
19)
The term semi–log refers to a graphical scale that has ________.
19)
A)
a linear axis and a log axis
B)
a linear vertical axis and a log horizontal axis
C)
a log–log structure
D)
All of the above
Answer:
A
A)
B)
C)
D)
20)
An amplifier normally has a power gain of 12,000. If the power gain of the circuit drops by 3 dB,
the value of the new power–gain will be approximately ________.
20)
A)
4,000
B)
zero
C)
6,000
D)
9,000
Answer:
C
A)
B)
C)
D)
21)
The input power to a device is 5000 W at 400 V. The output power of the device is 750 W, and the
output impedance is 25 . Calculate the power gain in decibles.
21)
A)
16.478 dB
B)
–16.478 dB
C)
8.239 dB
D)
–8.239 dB
Answer:
D
A)
B)
C)
D)
5
22)
Negative dB values represent ________.
22)
A)
power losses
B)
power gain
C)
power values that do not change
D)
None of the above
Answer:
A
A)
B)
C)
D)
23)
The base–10 logarithm of 100,000 is ________.
23)
A)
6
B)
5
C)
4
D)
None of the above
Answer:
B
A)
B)
C)
D)
24)
What is the proper equation for calculating the low frequency break point due to the capacitor CC
for this BJT amplifier.
24)
A)
fLC =1
2RCRLCC
B)
fLC =1
2(ro + RL)CC
C)
fLC =1
2Ro+RLCC=
D)
fLC =1
2RCCC
Answer:
C
A)
B)
C)
D)
6
25)
The high–frequency response of a BJT amplifier is affected by ________.
25)
A)
the supply voltage
B)
the BJT internal capacitances
C)
the coupling and bypass capacitor values
D)
All of the above
Answer:
B
A)
B)
C)
D)
26)
An amplifier with a gain of 40 has a bandwidth of 150 kHz. The unity gain frequency of this
amplifer is ________.
26)
A)
190 kHz
B)
212 kHz
C)
150 kHz
D)
6 MHz
Answer:
D
A)
B)
C)
D)
27)
Human hearing responds ________ to changes in loudness.
27)
A)
linearly
B)
inversely
C)
logarithmically
D)
exponentially
Answer:
C
A)
B)
C)
D)
28)
The low–frequency response of a BJT amplifier is affected by ________.
28)
A)
the BJT internal capacitances
B)
the coupling and bypass capacitor values
C)
the supply voltage
D)
All of the above
Answer:
B
A)
B)
C)
D)
29)
The input power to a device is 5000 W at 400 V. The output power of the device is 750 W, and the
output impedance is 25 . Calculate the voltage gain in decibles.
29)
A)
–9.311 dB
B)
4.6556 dB
C)
–4.6556 dB
D)
9.311 dB
Answer:
A
A)
B)
C)
D)
7
30)
Which of the following are properties of logarithms?
30)
A)
logn0 = 1
B)
logn(1/b) = –lognb
C)
logn(a/b) =logna+lognb
D)
None of the above
Answer:
B
A)
B)
C)
D)
31)
Miller capacitance affects
31)
A)
the low–frequency response
B)
both high and low–frequencies
C)
the high–frequency response
D)
only non–inverting amplifiers
Answer:
C
A)
B)
C)
D)
32)
At mid frequencies capacitve elements ________
32)
A)
primarily affects low frequency response
B)
affects both low and high frequency response
C)
are ignored
D)
primarily affects low frequency response
Answer:
C
A)
B)
C)
D)
33)
An amplifier has an output power of 500 W. What is the value of the power gain in dB for the
circuit?
33)
A)
56.99 dB
B)
53.98 dB
C)
26.99 dB
D)
Cannot be determined from the information given
Answer:
D
A)
B)
C)
D)
8
34)
When using square–wave testing on two different amplifiers, you see the waveforms shown here.
What comments can you make about the frequency response of the two amplifiers?
34)
A)
Amplifier A has poor high frequency response, while amplifier B has poor low frequency
response.
B)
Amplifier A has poor low frequency response, while amplifier B has poor high frequency
response.
C)
Amplifier A has poor low frequency response, while amplifier B has poor low frequency
response.
D)
Amplifier A has poor high frequency response, while amplifier B has poor high frequency
response.
Answer:
A
A)
B)
C)
D)
35)
If several identical stages of amplifiers, each having the exact same upper and lower cutoff
frequencies, are connected in cascade, then the bandwidth of the resulting amplifier will ________.
35)
A)
be equal to the sum of all the individual bandwidths
B)
remain unchanged
C)
increase
D)
decrease
Answer:
D
A)
B)
C)
D)
36)
Parasitic capacitance values primarily affect the ________ frequency range while coupling
capacitors affect the ________ range.
36)
A)
low, high
B)
low, low
C)
high. low
D)
hjigh, high
Answer:
C
A)
B)
C)
D)
9
37)
The input value of f1 for a FET amplifier normally is ________ the input value of f1 for a
comparable BJT amplifier.
37)
A)
greater than
B)
similar to
C)
less than or equal to
D)
much lower than
Answer:
B
A)
B)
C)
D)
38)
An amplifier has values of power gain = 49 dB and voltage gain = 30 dB. The operating frequency
of the circuit is increased until the power gain drops to 42 dB. What is the dB voltage gain at this
frequency?
38)
A)
42 dB
B)
25.7 dB
C)
23 dB
D)
Cannot be determined from the information given
Answer:
C
A)
B)
C)
D)
39)
The common log of the ratio of two power levels is called a ________.
39)
A)
big bel
B)
bel
C)
decibel
D)
None of the above
Answer:
B
A)
B)
C)
D)
40)
The Miller effect tends to ________ of an inverting amplifier.
40)
A)
decrease the input capacitance and increase the output capacitance
B)
decrease both the input and output capacitances
C)
increase both the input and output capacitances
D)
increase the input capacitance and decrease the output capacitance
Answer:
C
A)
B)
C)
D)
41)
Which of the following are properties of logarithms?
41)
A)
logn1 = 0
B)
logn(1/b ) = –lognb
C)
logn(a/b) =logna –lognb
D)
All of the above
Answer:
D
A)
B)
C)
D)
10
42)
Two identical amplifiers are cascaded. The overall bandwidth of the multistage amplifier is
________ the bandwidth of each individual stage.
42)
A)
less than or equal to
B)
less than
C)
greater than
D)
equal to
Answer:
B
A)
B)
C)
D)
43)
The gain in decibels of a power gain of 10,000,000 is ________.
43)
A)
6 dB
B)
70 dB
C)
80 dB
D)
5 dB
Answer:
B
A)
B)
C)
D)
44)
The roll–off rate for a BJT amplifier is approximately ________.
44)
A)
6 dB per decade
B)
6 dB per octave
C)
20 dB per octave
D)
None of the above
Answer:
B
A)
B)
C)
D)
45)
To fix the frequency boundaries of relatively high gain, 0.7 Amid was chosen to be at the cutoff
levels. The corresponding frequencies, f1 and f2, are generally called ________.
45)
A)
half–power frequencies
B)
cutoff frequencies
C)
corner frequencies
D)
All of the above
Answer:
D
A)
B)
C)
D)
11
Answer Key
Testname: C9
1)
D
2)
B
3)
C
4)
A
5)
D
6)
C
7)
A
8)
B
9)
B
10)
A
11)
B
12)
A
13)
C
14)
B
15)
D
16)
C
17)
A
18)
C
19)
A
20)
C
21)
D
22)
A
23)
B
24)
C
25)
B
26)
D
27)
C
28)
B
29)
A
30)
B
31)
C
32)
C
33)
D
34)
A
35)
D
36)
C
37)
B
38)
C
39)
B
40)
C
41)
D
42)
B
43)
B
44)
B
45)
D