Deck 18: Linear OP AMP Circuits

Question 1

The reversible and adjustable gain op amp circuit is the type of circuit that can be just as easily configured using discrete components.

Answer 1

False

Question 2

A differential amplifier is often used in applications in which the differential input signal is a large dc voltage (volts)and the common-mode input signal is a small dc voltage (millivolts).

Answer 2

False

Question 3

Differential inputs often use a first stage of two voltage followers in order to

A) provide more voltage gain.
B) reduce input resistance.
C) buffer the inputs.
D) directly connect the inputs.

Answer 3

C

Question 4

Using a bypass capacitor in an ac-coupled noninverting op amp minimizes the output offset voltage.

Question 5

Linear op amp circuits include inverting amps,differential amps,instrumentation amps,and current boosters.

Question 6

The output of a linear op amp circuit has the same shape as the input signal.

Question 7

Advantages of a noninverting op amp circuit include stable voltage gain,high input impedance,and low output impedance.

Question 8

An ac-coupled amplifier needs a frequency response down to zero hertz.

Question 9

When an input signal drives both inputs of an op amp,both inverting and noninverting amplification results and the output is the superposition of two amplified signals.

Question 10

The voltage gain of a circuit known as a sign changer can be varied from -1 to 1.

Question 11

The LED that converts current into light is an example of

A) a transformer.
B) an input transducer.
C) an output transducer.
D) a converter.

Question 12

A device that converts a nonelectrical quantity into an electrical quantity is

A) a transformer.
B) an input transducer.
C) an output transducer.
D) a converter.

Question 13

For a 741C op amp,the minimum CMRR is 70 dB at low frequencies.

Question 14

The total voltage gain with an input driving both sides of an op amp equals the voltage gain of the inverting channel times the voltage gain of the noninverting channel.

Question 15

One of the most important characteristics of a differential amplifier is its CMRR.

Question 16

A Wheatstone bridge is balanced when

A) the ratio of resistances on the left side equals the ratio of resistances on the right side.
B) the ratio of resistances on the left side is less than the ratio of resistances on the right side.
C) the ratio of resistances on the left side is greater than the ratio of resistances on the right side.
D) the ratio of resistances on both sides equals the square root of the sum of all resistances.

Question 17

Because the output of a Wheatstone bridge is a small dc voltage with a large common-mode voltage,what type of amp must be used?

A) dc with a very high CMRR
B) ac with a very high CMRR
C) a power amp
D) a voltage follower

Question 18

A voltage reference is a circuit that produces an extremely accurate and stable output voltage.

Question 19

The op amp phase shifter circuit produces an output voltage with the same magnitude as the input voltage,but with a phase angle that can be varied continuously between 0° and -180°.

Question 20

One advantage of the inverting op amp is that its voltage gain equals the ratio of the input resistance to the feedback resistance.

Question 21

When the input and output voltages of an op amp can swing all the way to the positive or negative supply voltages,what condition results?

A) floating load
B) guard driving
C) rail-to-rail operation
D) laser trimming

Question 22

Burning off resistor areas on a semiconductor chip with a laser in order to get an extremely precise value of resistance is referred to as

A) laser trimming.
B) resistor chipping.
C) buffering.
D) guard driving.

Question 23

The characteristics of an instrumentation amplifier does not include

A) large voltage gain.
B) low input offsets.
C) low temperature drift.
D) low input impedance.

Question 24

The method most often used in integrated circuit D/A converters is the

A) binary-weighted D/A converter.
B) R/2R ladder D/A converter.
C) binary ladder D/A converter.
D) R/2R weighted converter.

Question 25

What is used to automatically change the voltage gain when the input signal changes?

A) automatic gain control
B) automatic feedback system
C) open-loop gain control
D) automated stepping voltage

Question 26

Which of the following is not an advantage of a noninverting op amp?

A) stable voltage gain
B) low input impedance
C) low output impedance
D) high input impedance

Question 27

A circuit that subtracts two input voltages to produce an output voltage equal to the difference of the two input signals is called a ________.

A) summing amp
B) converter
C) comparator
D) subtracter

Question 28

A monolithic instrumentation amplifier typically has a CMRR of over ________.

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

Question 29

What type circuit takes a binary represented value and converts it into a voltage or current?

A) analog-to-digital converter
B) digital-to-analog converter
C) digital step converter
D) analog ladder converter

Question 30

When a power transistor with a higher current gain and rating than an op amp is used to get more short-circuit output current,it is referred to as

A) a constant current source.
B) a power amp.
C) a current booster.
D) a short-circuit amp.

Question 31

The output impedance of an emitter follower can be reduced by using

A) a large load resistor.
B) negative feedback.
C) positive feedback.
D) a large input resistor.

Question 32

A circuit that produces an extremely accurate and stable value of output voltage is called

A) a constant voltage source.
B) a D/A circuit.
C) a voltage reference.
D) a voltage divider.

Question 33

Linear op amp circuits do not include

A) differential amps.
B) instrumentation amps.
C) multiplexers.
D) current boosters.

Question 34

In applications where the number of inputs are limited and where high precision is not required

A) the binary-weighted D/A converter is typically used.
B) the R/2R ladder D/A converter is typically used.
C) the binary summing adder is typically used.
D) the A/D ladder is typically used.

Question 35

The process of minimizing the effects of leakage current and cable capacitance by bootstrapping the shield to the common-mode potential is called

A) laser trimming.
B) booting capacitance.
C) buffering.
D) guard driving.

Question 36

The binary-weighted D/A converter produces an output voltage equal to

A) the weighted sum of the inputs.
B) the most significant bit.
C) one of sixteen unique voltage levels.
D) product of input resistance and voltage.

Question 37

With an ac coupled op amp circuit,the output offset voltage can be minimized by using

A) a bypass capacitor.
B) a coupling capacitor.
C) a low pass filter.
D) a pi filter.

Question 38

Op amp power supply ripple and noise appearing on the noninverting input is reduced by adding

A) an emitter follower.
B) a large input resistor.
C) a bypass capacitor.
D) other supply voltage.

Question 39

The output of a linear op amp circuit

A) is always nonlinear.
B) is distorted due to saturation.
C) has the same shape as the input signal.
D) is always digital.

Question 40

In order to provide a smoother transition between the output steps produced by a D/A converter,what circuit is typically connected to the output?

A) current booster
B) floating load
C) high-pass filter
D) low-pass filter

Question 41

In the circuit shown in Figure 18-33,the JFET functions as a

A) voltage-controlled resistance.
B) power amplifier.
C) voltage regulator.
D) preamp.

Question 42

When the feedback and input resistances of an op amp are equal,the inverting amplifier has a closed-loop gain of ________.

A) -R/R
B) R/R
C) 1
D) -10

Question 43

In order to have high CMRR and offsets,what type op amp is required when building an instrumentation amplifier?

A) 741C
B) precision
C) standard
D) linear

Question 44

An op amp circuit that can produce a variable voltage gain from −1 to 1 is called

A) a gain changer.
B) a reverse voltage changer.
C) a sign changer.
D) variable voltage changer.

Question 45

One of the most important characteristics of a differential amplifier is its

A) voltage gain.
B) input resistance.
C) output resistance.
D) CMRR.

Question 46

Aside from the op amp's CMRR,another source of common-mode error is the

A) tolerance of resistors.
B) value of the coupling capacitors.
C) amount of voltage gain.
D) wattage of the resistors.

Question 47

Which op amp circuit produces an output voltage with the same magnitude as the input voltage,but with a phase angle that can be varied continuously between 0° and −180°?

A) inverter
B) converter
C) phase shifter
D) comparator

Question 48

The total voltage gain with an input signal driving both sides of an op amp equals the voltage gain of the inverting channel

A) plus the voltage gain of the noninverting channel.
B) minus the voltage gain of the noninverting channel.
C) only.
D) times the voltage gain of the noninverting channel.

Question 49

When an input signal drives both inputs of an op amp,both inverting and noninverting amplification occur at the same time and the output is the

A) sum of the two amplified signals.
B) product of the two amplified signals.
C) Thevenin's voltage of the two amplified signals.
D) superposition of the two amplified signals.

Question 50

What transducer converts a change in temperature into a change in resistance?

A) thermometer
B) thermocouple
C) thermistor
D) thyristor