Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1)
This circuit represents a(n) ________.
1)
A)
totem pole, or tri–state, output
B)
regular output of an op–amp
C)
open–drain output
D)
open–collector output
Answer:
A
A)
B)
C)
D)
2)
What is the ideal output of this 741 op–amp comparator when the input is 1.5 V?
2)
A)
– 2 V
B)
+ 2 V
C)
– 5 V
D)
+ 5 V
Answer:
C
A)
B)
C)
D)
1
3)
The positive pulse width for this circuit is mainly determine by ________.
3)
A)
the values of RA and C
B)
the value of +Vcc
C)
the amplitude of the trigger waveform
D)
None of the above
Answer:
A
A)
B)
C)
D)
4)
An 8–stage D/A converter has a reference voltage of +12 V. What is the resolution of the converter?
4)
A)
666.7 mV
B)
47.0 mV
C)
comparator
D)
46.875 mV
E)
1.5 V
Answer:
D
A)
B)
C)
D)
E)
5)
The ladder network for digital–to–analog conversion uses resistors ________.
5)
A)
that have a ratio that is 1 : 2 : 4 : 8 : . . ., depending on how many legs you need for the ladder
B)
that are required to be very precise
C)
that are wire–wound so they can carry a large current
D)
that have a ratio that is 2 : 1, but the actual value is not very important
Answer:
D
A)
B)
C)
D)
2
6)
Which one of the following is most closely associated with a R–2R ladder network?
6)
A)
555 timer
B)
comparator
C)
D/A converter
D)
PLL
Answer:
C
A)
B)
C)
D)
7)
Which of the following expressions indicates the frequency of the output waveform from a 555
astable multivibrator?
7)
A)
0.7RBC
B)
1.1RAC
C)
0.7 RA+RBC
D)
1.44
RA+2RBC
Answer:
D
A)
B)
C)
D)
8)
The circuit shown here is a ________.
8)
A)
zero crossing detector
B)
level detector
C)
door detector
D)
window detector
Answer:
D
A)
B)
C)
D)
3
9)
This circuit represents a(n) ________.
9)
A)
regular output of an op–amp
B)
open–drain output
C)
totem–pole, or tri–state, output
D)
open–collector output
Answer:
D
A)
B)
C)
D)
10)
In a simple 556 VCO application, increasing the time constant of the external capacitor and resistor
causes the output frequency to ________. (Assume all other variables remain unchanged.)
10)
A)
increase
B)
The answer cannot be determined without knowing the ratio of input–to–supply voltage.
C)
There will be no significant change.
D)
decrease
Answer:
D
A)
B)
C)
D)
11)
In the dual–slope A/D converter, the second slope (the one that discharges the capacitor) ________.
11)
A)
has a constant slope until the capacitor discharges to a predetermined level
B)
has a constant slope over a fixed time interval
C)
has a constant slope
D)
is at a constant voltage level
Answer:
A
A)
B)
C)
D)
4
12)
The input voltage at the noninverting terminal of this comparator is greater than the reference
voltage at the inverting terminal. What is the status of the output?
12)
A)
equal to V–
B)
equal to V+
C)
open circuit
D)
short circuit
Answer:
B
A)
B)
C)
D)
13)
When the input to this circuit is more than 5 V, the ideal output is ________.
13)
A)
9 V
B)
open circuit
C)
0 V
D)
The input voltage is not allowed to be more than 5 V.
Answer:
C
A)
B)
C)
D)
5
14)
Capacitor C in this circuit both charges and discharges through ________.
14)
A)
terminal 7
B)
RB
C)
RA
D)
RA and RB
Answer:
B
A)
B)
C)
D)
15)
A common application of the PLL is ________.
15)
A)
FM demodulation
B)
demodulation of two carrier frequencies
C)
frequency synthesis
D)
All of the above
Answer:
C
A)
B)
C)
D)
16)
A circuit that provides an output signal at the voltage and/or current levels suitable for operating a
particular load is called a(n) ________.
16)
A)
polarizer
B)
RS–232C
C)
driver
D)
None of the above
Answer:
C
A)
B)
C)
D)
6
17)
When the input voltage to this circuit is more than 1 V, but less than 5 V, the ideal output is
________.
17)
A)
9 V
B)
0 V
C)
open circuit
D)
The input is not allowed to be in the specified voltage range.
Answer:
A
A)
B)
C)
D)
18)
Which of the following expressions indicates the duration of the output pulse from a 555
monostable multivibrator?
18)
A)
1.1RAC
B)
1.44
RA+2RBC
C)
0.7RBC
D)
0.7 RA+RBC
Answer:
A
A)
B)
C)
D)
19)
A 555 monostable multivibrator begins it timing cycle ________.
19)
A)
on the negative–going edge of the input trigger waveform
B)
on the positive–going edge of the input trigger waveform
C)
at intervals determined by the values of R and C
D)
in the lock range
Answer:
A
A)
B)
C)
D)
7
20)
A comparator has a ________.
20)
A)
digital input and a digital output
B)
linear input and a linear output
C)
linear input and a digital output
D)
digital input and a linear output
Answer:
C
A)
B)
C)
D)
21)
The output of a 311 comparator is taken from ________ so that it can be used to drive a variety of
loads such as a lamp or a relay.
21)
A)
the noninverting input of the op–amp
B)
the output pin of the op–amp
C)
a bipolar transistor
D)
the strobe pins of the op–amp
Answer:
C
A)
B)
C)
D)
22)
Which of the following expressions indicates the low–time for the output from a 555 astable
multivibrator?
22)
A)
1.44
RA+2RBC
B)
0.7RBC
C)
1.1RAC
D)
0.7 RA+RBC
Answer:
B
A)
B)
C)
D)
23)
In the 566 VCO, the output frequency is controlled by the external ________.
23)
A)
resistor
B)
input voltage
C)
capacitor
D)
All of the above
Answer:
D
A)
B)
C)
D)
8
24)
When the input to this circuit is less than 1 V, the ideal output is ________.
24)
A)
0 V
B)
open circuit
C)
9 V
D)
The input is not allowed to be less than 1 V.
Answer:
A
A)
B)
C)
D)
25)
This 555 IC is being used as a(n) ________.
25)
A)
VCO
B)
one–shot multivibrator
C)
PLL
D)
astable flip–flop
Answer:
B
A)
B)
C)
D)
9
26)
The output of this 311 comparator changes state when the input voltage ________.
26)
A)
crosses 0V Volts in any direction
B)
crosses 0V and going from negative to positive only
C)
crosses 0 V and going from positive to negative only
D)
None of the above
Answer:
A
A)
B)
C)
D)
27)
A circuit that contains a phase detector, a low–pass filter, and a VCO is a(n) ________.
27)
A)
astable multivibrator
B)
phase–locked loop
C)
comparator
D)
None of the above
Answer:
B
A)
B)
C)
D)
28)
In the dual–slope A/D converter, the first slope (the one that charges the capacitor) ________.
28)
A)
has a constant slope over a fixed time interval
B)
has a constant slope
C)
has a slope until the capacitor charges to a predetermined level
D)
is at a constant voltage level
Answer:
C
A)
B)
C)
D)
29)
Which of the following is an application of the 566 IC?
29)
A)
monostable multivibrator
B)
VCO
C)
astable multivibrator
D)
Comparator
Answer:
B
A)
B)
C)
D)
10
30)
Which of the following represents an improvement in comparators due to IC technology?
30)
A)
variety of output drive capability
B)
built–in noise immunity
C)
faster switching
D)
All of the above
Answer:
D
A)
B)
C)
D)
31)
When a sinusoidal waveform is applied to the modulating input a basic 566 VCO, the output
frequency increases ________.
31)
A)
whenever the input crosses through zero in either direction
B)
as the input goes more positive
C)
as the input goes more negative
D)
The answer cannot be determined without knowing the values of R and C for the circuit.
Answer:
C
A)
B)
C)
D)
32)
This 555 IC circuit is a(n) ________.
32)
A)
monostable flip–flop
B)
bistable flip–flop
C)
phase–locked loop
D)
free–running oscillator
Answer:
D
A)
B)
C)
D)
11
33)
This figure is a block diagram of a(n) ________.
33)
A)
PLL
B)
frequency synthesizer
C)
A/D converter
D)
555 timer
Answer:
B
A)
B)
C)
D)
34)
Which of these is an application of the 555 IC?
34)
A)
D/A converter
B)
astable multivibrator
C)
A/D converter
D)
comparator
Answer:
B
A)
B)
C)
D)
35)
Typical gain of a comparator is ________.
35)
A)
100
B)
100,000
C)
10,000
D)
1000
Answer:
B
A)
B)
C)
D)
36)
The 555 timer can be used as a(n) ________.
36)
A)
astable multivibrator
B)
monostable multivibrator
C)
pulse width modulator
D)
All of the above
Answer:
D
A)
B)
C)
D)
37)
Which of the following expressions indicates the high–time for the output from a 555 astable
multivibrator?
37)
A)
0.7 RA+RBC
B)
1.44
RA+2RBC
C)
0.7RBC
D)
1.1RAC
Answer:
A
A)
B)
C)
D)
12
38)
This figure is a block diagram of a(n) ________.
38)
A)
555 timer
B)
PLL
C)
frequency synthesizer
D)
A/D converter
Answer:
B
A)
B)
C)
D)
39)
Resistor RB and capacitor C in this circuit determine ________.
39)
A)
output dc voltage level
B)
high time of the output waveform
C)
output phase
D)
low time of the output waveform
Answer:
B
A)
B)
C)
D)
40)
Decreasing the +Vcc supply voltage for a 555 free–running oscillator causes ________.
40)
A)
causes a positive shift in the output phase
B)
no significant change in the output frequency
C)
the output frequency to increase
D)
the output frequency to decrease
Answer:
B
A)
B)
C)
D)
13
Answer Key
Testname: C13
1)
A
2)
C
3)
A
4)
D
5)
D
6)
C
7)
D
8)
D
9)
D
10)
D
11)
A
12)
B
13)
C
14)
B
15)
C
16)
C
17)
A
18)
A
19)
A
20)
C
21)
C
22)
B
23)
D
24)
A
25)
B
26)
A
27)
B
28)
C
29)
B
30)
D
31)
C
32)
D
33)
B
34)
B
35)
B
36)
D
37)
A
38)
B
39)
B
40)
B