Deck 16: Regulators, Filters, and Op-Amps

Question 1

Op-amp comparators are often used as zero-level detectors.

Answer 1

True

Question 2

An op-amp summing amplifier has no limitations on the number of inputs it can handle.

Answer 2

True

Question 3

If the two input voltages are 9.2 V and 0.7 V in Figure 19-2(a),W hat is the output voltage?

A)-8.5V
B)-9.9V
C)8.5V
D)9.9V

Answer 3

-9.9V

Question 4

$$\text { Figure } \mathbf { 1 9 } < \mathbf { 1 }$$

-If V_IN equals 8 V in Figure 19-1, V_OUT equals_______

A) -1 V
B) 1 V
C) 13 V
D) -13 V

Question 5

A series-pass transistor is used in a voltage regulator.

Question 6

$$\text { Figure } \mathbf { 1 9 } < \mathbf { 1 }$$

-If V_IN equals 4 V in Figure 19-1, V_OUT equals__________

A) -13 V
B) 13 V
C) -1 V
D) 1 V

Question 7

If the inputs are 8.4 V and 1.2 V in Figure 19-2(a), the output voltage equals ________.

A)9.6V
B)-9.6V
C)10.08V
D)7.2V

Question 8

What change causes the circuit in Figure 19-2(b) to output the average of the three input voltages?

A) Change the input resistors to 3.3
B) Change the feedback resistor to 3.3
C) Change to a different type of op-amp.
D) Change the feedback resistor to 10

Question 9

If the inputs are -7.1 V and 12 V in Figure 19-2(a),W hat is the output voltage?

A)4.9V
B)-4.9V
C)19.1V
D)-19.1V

Question 10

Butter worth filters are characterized by a linear response in the pass band.

Question 11

$$\text { Figure } \mathbf { 1 9 } < \mathbf { 1 }$$

-If V_IN=-3 V in Figure 19-1, V_OUT equals________

A) -13 V
B) 13 V
C) -1 V
D) 1 V

Question 12

Hartley and Colpitts oscillators can use op-amps.

Question 13

The terminals on a three-terminal regulator are input voltage, output voltage and ground.

Question 14

$$\text { Figure } \mathbf { 1 9 } < \mathbf { 1 }$$

-If V_IN=8.3 V in Figure 19-1, V_OUT e quals________

A) 3.3 V
B) -3.3 V
C) -13 V
D) 13 V

Question 15

If the inputs are 4.1 V, -0.7 V and 3.1 V in Figure 19-2(b), the output voltage equals ________.

A)-6.5V
B)13V
C)-13V
D)6.5V

Question 16

$$\text { Figure } \mathbf { 1 9 } < \mathbf { 1 }$$

-If V_IN=4.2 V in Figure 19-1, V_OUT equals__________

A) -0.8 V
B) 0.8 V
C) 13 V
D) -13 V

Question 17

An op-amp integrator Will produce a linear increasing output voltage for a constant negative input voltage until cutoff is reached.

Question 18

An op-amp comparator can be used to determineW hen an input voltage crosses a certain reference Voltage.

Question 19

$$\text { Figure } \mathbf { 1 9 } < \mathbf { 1 }$$

-If V_IN=-2 V in Figure 19-1, V_OUT equals______

A) 13 V
B) -3 V
C) 3 V
D) -13 V

Question 20

A second-order filter rolls-off at 40 dB/decade.

Question 21

$$\text { Figure } 19 < 4$$

-The circuit in Figure 19-4 is known as the____ and it rolls off at a rate of________

A) Butterworth high-pass filter, -40 dB /decade
B) Butterworth low-pass filter, -40 dB/decade
C) Butterworth low-pass filter, -20 dB/decade
D) Butterworth high-pass filter, -20 dB/decade

Question 22

The curve in Figure 19-5 is from a ________ and its lower cutoff frequency equals ________.

A)two-pole high-pass filter, 1500 Hz
B)band-reject filter, 450 kHz
C)band-pass filter, 822 Hz
D)band-pass filter, 450 Hz

Question 23

$$\text { Figure } 19 < 3$$

-If R=1.2 $\mathrm { k } \Omega$ and C=0.005 $\mu \mathrm { F }$ in Figure 19-3, the $\mathrm { fCO }$ equals________

A) 65 Hz
B) 650 Hz
C) 26.5 kHz
D) 2.65 kHz

Question 24

In Figure 19-3,W hatW ill change the circuit into a high-pass filter?

A)increasing theV
Alue of the resistor
B)switching the positions of the resistor and capacitor
C)decreasing theV
Alue of the capacitor
D)placing the capacitor in the feedback loop

Question 25

$$\text { Figure } 19 < 3$$

-If R=47 $\mathrm { k } \Omega$ and C=0.02 $\mu \mathrm { F }$ in Figure 19-3, $\mathrm { fCO }$ equals______

A) 5.19 Hz
B) 16.9 Hz
C) 169 Hz
D) 51.9 Hz

Question 26

$$\text { Figure } 19 < 3$$

-If R=1.5 $\mathrm { k } \Omega$ and C=256 pF in Figure 19-3 , the f_CO equals_______

A) 41.4 kHz
B) 25.7 Hz
C) 257 Hz
D) 414 kHz

Question 27

$$\text { Figure } 19 < 3$$

-If R=56 $\mathrm { k } \Omega$ and C=0.05 $\mu \mathrm { F }$ in Figure 19-3, $\mathrm { fCO }$ equals_____

A) 568 Mz
B) 56.8 Hz
C) 3.0 Hz
D) 300 Hz

Question 28

If 22 V in the pass-band is input to the circuit in Figure 19-4,W hat is the output voltage at fCO?

A)8.92V
B)7.75V
C)31.1V
D)15.6V

Question 29

If the inputs are 1.2 V, -0.5 V and 2.4 V in Figure 19-2(b),W hat is the output voltage?

A)13V
B)-6.2V
C)6.2V
D)-4.1V

Question 30

A three-terminal voltage regulator ________.

A)comes in a variety of Voltage and current ratings
B)is available in both positive and negative Voltage ratings
C)is very durable
D)all of the above

Question 31

$$\text { Figure } 19 < 3$$

-If V_IN equals 22 V in Figure 19-3, V_OUT at the f_CO equals______

A) 31.1 V
B) 15.64 V
C) 0
D) 7.79 V

Question 32

$$\text { Figure } 19 < 3$$

-If V_IN=70 V_P in Figure 19-3, the output voltage at f_CO equals______

A) 13 VP
B) 0 VP
C) 49.5 VP
D) 44.2 VP

Question 33

If VOUT equals 12 V at 822 Hz in Figure 19-5, the output voltage equals ________ at 450 Hz.

A)4.24V
B)1.06V
C)8.49V
D)2.12V

Question 34

If 22 V in the pass-band is input to the circuit in Figure 19-4,W hat is the output voltage at a frequency that is 1 decade higher?

A)31.1V
B)22V
C)7.75V
D)15.5V

Question 35

In Figure 19-4, if the frequency is decreased from the pass band to 1 decade below fCO, the output voltage drops to ________.

A)-40 dB
B)-6 dB
C)-3 dB
D)-20 dB

Question 36

$$\text { Figure } 19 < 3$$

-If R=22 $\mathrm { k } \Omega$ and C=0.05 $\mu \mathrm { F }$ in Figure 19-3, f_CO equals________

A) 145 Hz
B) 4.8 Hz
C) 48 Hz
D) 1.45 kHz

Question 37

$$\text { Figure } 19 < 4$$

-The prime characteristic of the filter in Figure 19-4 is ________.

A)it only works in a high-pass configuration
B)the filter roll-off below the corner frequency is 40 dB/decade
C)it has the largest response of any filter type
D)nothing special

Question 38

The frequency response curve in Figure 19-5 represents the output from the ________, and the bandwidth is ________.

A)band-pass filter, 1050 Hz
B)band-pass filter, 678 Hz
C)band-reject filter, 1050 kHz
D)two-pole high-pass filter, 1050 Hz

Question 39

If the output voltage is 6 V at 1500 Hz in Figure 19-5,W hat is the output voltage at 822 Hz?

A)4.24V
B)1.06V
C)8.49V
D)2.12V

Question 40

If the output voltage is 27.4 V at 822 Hz in Figure 19-5,W hat is the output voltage at 1.5 kHz?

A)27.4V
B)13.7V
C)6.85V
D)19.4V

Question 41

A series-pass voltage regulator has ________.

A)a load
B)a shunt regulator
C)an error amplifier
D)all of these

Question 42

A series and a shunt regulator are differentiated by the circuit placement of a:

A)series resistor versus parallel resistor.
B)series transistor versus parallel transistor.
C)series reference Voltage versus parallel reference Voltage.
D)none of these.

Question 43

In a series voltage regulator, the four circuit blocks are:

A)error detector, referenceVoltage, series regulator, sampling circuit.
B)control element, referenceVoltage, error detector, sampling circuit.
C)referenceVoltage, series load, referenceVoltage, current limiter.
D)control element, referenceVoltage, error detector, current limiter.

Question 44

At the cutoff frequency of a filter circuit, the output voltage is:

A)-20 dB.
B)-40 dB.
C)-3 dB.
D)-10 dB.

Question 45

Short-circuit or overload protection is an integral part of

A) most JFETs
B) most three-terminal regulators
C) most op-amps
D) most TRIACs

Question 46

The output of an op-amp differentiator depends on the values of ________ and ________.

A)CIN, CF
B)RIN, RF
C)RIN, CF
D)CIN, RF

Question 47

In an inverting input op-amp, differentiator suppliedW ith a ramp or triangularW ave, the output is a:

A)opposite phase ramp.
B)same phase square Wave.
C)sine Wave.
D)opposite phase square Wave.

Question 48

The purpose of a comparator is to ________.

A)detect the occurrence of a changing input voltage
B)produce a change in output when an input voltage equals a reference voltage
C)maintain a constant output when the dc inputVoltage changes
D)amplify an input voltage

Question 49

Using op-amps in a triangularW ave oscillator results in a:

A)triangular Wave output.
B)function generator output.
C)square Wave output.
D)all of these.

Question 50

If all four input resistors to a summing amplifier are 2.2 $\mathrm { k } \Omega$ and the feedback resistor is 2.2 $\mathrm { k } \Omega$ . then the gain equals________

A) 4
B) 2.2
C) 1
D) unknown

Question 51

In a scaling adder, the ________.

A)input resistors have values depending on the assigned weight of each input
B)input resistors are all different values
C)input resistors are all the same value
D)ratio RF/RIN must be the same for each input

Question 52

In a filter circuit, the terminology single pole means:

A)one fixed contact.
B)one single RC circuit.
C)one movable contact.
D)two cascaded RC circuits.

Question 53

The basic op-amp squareW ave oscillator is actually a:

A)Wein-bridge oscillator.
B)resistor-capacitor (RC)time constant oscillator.
C)sine Wave oscillator.
D)all of these.

Question 54

The input frequency of a single-pole, low-pass active filter increases from 1.5 kHz to 150 kHz. If the critical frequency is 1.5 kHz, the gain decreases by ________.

A)60 dB
B)3 dB
C)40 dB
D)20 dB

Question 55

If an inverting amplifier has a capacitor in the feedback loop, the circuit is known as the ________. When a square wave input is applied, the output is a ________wave.

A)integrator, square
B)open loop, triangle
C)differentiator, triangle
D)integrator, triangle

Question 56

The ideal amplifier has infinite gain, infinite input impedance, and zero output impedance.

Question 57

In a Wein-bridge op-amp oscillator, the output is a repetitive:

A)square Wave.
B)sine Wave.
C)triangular Wave.
D)all of these.

Question 58

In a voltage-controlled oscillator (VCO), the output signal frequency is dependent on:

A)the value of a resistor-capacitor combination.
B)the value of a resistor.
C)the value of an applied Voltage.
D)the value of a capacitor.

Question 59

In an inverting input op-amp integrator suppliedW ith a squareW ave pulse or a step, the output is a:

A)opposite phase ramp.
B)same phase ramp.
C)opposite phase square Wave.
D)sine Wave.

Question 60

If all four input resistors to a summing amplifier are 2.2 $\mathrm { k } \Omega$ , the feedback resistor is 2.2 $\mathrm { k } \Omega$ and all four input voltages are -2 V , the output voltage equals_______

A) 2 V
B) 2.2 V
C) 8 V
D) 10 V

Question 61

The open-loop voltage gain of an op-amp is very large.

Question 62

If and in Figure 18-1(c), the voltage gain equals

A) -38.3
B) -1
C) -39.3
D) infinite

Question 63

Figure $18 < 1$

-VRF equals____ in Figure 18-1(c).

A) V_RI
B) V_OUT
C) V_IN
D) V_CC

Question 64

The slew rate of an op-amp is determined by the frequency response of the internal amplifiers.

Question 65

Which one of these op-amp terminals provides an output that is in-phase with the input?

A) offset null
B) non-inverting
C) V_CC
D) inverting

Question 66

What is the voltage gain of the amplifier in Figure 18-1(a)?

A)1000
B)1
C)100,000
D)10

Question 67

Identify the open-loop amplifier in Figure 18-1.

A)Figure 18-1(a)
B)Figure 18-1(b)
C)Figure 18-1(c)
D)none of these

Question 68

A voltage-follower op-amp has a voltage gain greater than one.

Question 69

Figure $18 < 1$

-If $\mathrm { R } _ { f } = 0.5 \mathrm { M } \Omega$ and $\mathrm { R } _ { \mathrm { i } } = 10 \mathrm { k } \Omega$ in Figure 18-1(b), the voltage gain equals________

A) 6
B) 5
C) 50
D) 51

Question 70

Figure $18 < 1$

-If $\mathrm { R } _ { f } = 470 \mathrm { k } \Omega$ and $\mathrm { Ri } _ { \mathrm { i } } = 5 \mathrm { k } \Omega$ in Figure 18-1(b), the voltage gain equals_________

A) 1.01
B) 470
C) 94
D) 95

Question 71

An op-ampʹs input offset voltage, VOS, is the differential input voltage required to make the differential output voltage zero.

Question 72

An op-ampW ith a low CMRR easily rejects noise signals that appear at both inputs.

Question 73

Differential amplifiers provide high voltage gain and low common-mode rejection.

Question 74

Practical op-amps come reasonably close to the requirements for an ideal amplifier.

Question 75

An op-ampʹs CMRR is usually expressed in dB.

Question 76

The circuit in Figure 18-1(c)is known as the ________.

A)open-loop amplifier
B)voltage follower amplifier
C)non-inverting amplifier
D)inverting amplifier

Question 77

Figure $18 < 1$

-If $\mathrm { R } _ { f } = 1.2 \mathrm { M } \Omega$ and A_V=120 in Figure 18-1( c), Ri equals___________

A) 1 $\mathrm { k } \Omega$
B) 10 $\mathrm { k } \Omega$
C) 120 $\Omega$
D) 100 $\mathrm { k } \Omega$

Question 78

A typical value of input bias current for an op-amp is around 80 nA.

Question 79

Identify the non-inverting amplifier in Figure 18-1.

A)Figure 18-1(a)
B)Figure 18-1(b)
C)Both A and B
D)Neither of these

Question 80

Which of the amplifiers in Figure 18-1W ould be used as a buffer amplifier?

A)Figure 18-1(a)
B)Figure 18-1(b)
C)Figure 18-1(c)
D)none of these