Deck 16: Operational Amplifiers

Question 1

The 741C is the least expensive and most widely used op amp.

Answer 1

True

Question 2

The highest frequency that can be amplified without slew-rate distortion is sometimes called

A) resonant frequency.
B) half-power point.
C) power bandwidth.
D) cutoff frequency.

Answer 2

C

Question 3

The 741C op amp has an open-loop voltage gain of approximately ________.

A) 200
B) 2000
C) 20,000
D) 200,000

Answer 3

D

Question 4

The unity-gain frequency of an op amp is the frequency at which the voltage gain equals 100.

Question 5

An op amp consists of a diff amp as the input stage,followed by more stages of gain,and a class B push-pull emitter follower.

Question 6

Active loading is very popular in ICs because it is easier and less expensive to fabricate transistors on a chip than it is to fabricate resistors.

Question 7

The best way to eliminate output error and minimize thermal drift of an op amp is by using a nulling circuit.

Question 8

The short-circuit output current as listed on an op amp's data sheet,is the maximum output current the op amp can produce.

Question 9

The fastest response that an op amp can have is represented by its

A) slew rate.
B) frequency response.
C) compensating capacitor.
D) voltage gain.

Question 10

The ideal op amp has infinite voltage gain,infinite unity-gain frequency,infinite input impedance,and infinite CMRR.

Question 11

When higher input resistance is required,a designer would most probably use a BIFET op amp.

Question 12

Most op amps available today are low-power devices with a maximum power rating of less than a watt.

Question 13

For a 741C op amp,CMRR is 20 dB at low frequencies.

Question 14

What is used to stabilize the overall voltage gain of the inverting op amp circuit?

A) compensating frequencies
B) positive feedback
C) negative feedback
D) regenerative feedback

Question 15

A typical op amp has a single-ended input and a differential output.

Question 16

By connecting two external capacitors,op amp voltage gain and bandwidth can be adjusted to exact requirements.

Question 17

All op amps are internally compensated in order to prevent oscillations.

Question 18

The change in the output voltage of an op amp divided by the change in time is referred to as ________.

A) slew rate
B) nulling
C) frequency
D) bootstrapping

Question 19

The compensating capacitor inside a 741C op amp prevents oscillations that would interfere with the desired signal.

Question 20

When an op amp has no feedback path or loop,the voltage gain is minimum.

Question 21

The block diagram stages of an op amp does not include

A) a diff amp.
B) voltage regulator.
C) amplifiers.
D) emitter follower.

Question 22

What causes the open-loop bandwidth or cutoff frequency of an op amp to be very low?

A) negative feedback
B) positive feedback
C) high voltage gain.
D) internal compensating capacitor

Question 23

The voltage gain formula for a closed-loop op amp is ________.

A) R_f / R₁ + 1
B) R_f / R₁
C) R_f x R₁
D) R_f x R₁ + 1

Question 24

Op amp voltage gain and bandwidth can be adjusted to exact requirements by connecting

A) two external resistors.
B) an external compensating capacitor.
C) two external capacitors.
D) two power supplies.

Question 25

What type of op amp circuit uses feedback to stabilize the overall gain,increase the input impedance,and decrease the output impedance?

A) inverting
B) noninverting
C) comparator
D) mixer

Question 26

The characteristics of an ideal op amp does not include

A) infinite voltage gain.
B) infinite input impedance.
C) infinite output impedance.
D) infinite CMRR.

Question 27

In most operational amplifiers the output is

A) differential.
B) single-ended.
C) a Class C amplifier.
D) high impedance.

Question 28

What is the preferred surface-mount style used for most op amps?

A) dual-outline package.
B) small outline package.
C) large outline package.
D) single-inline package.

Question 29

Typical IC voltage regulators such as the LM340 can hold the dc output voltage to within what percent for normal changes in line voltage and load resistance?

A) 0.01 percent.
B) 0.1 percent.
C) 1.0 percent.
D) 10 percent.

Question 30

IC amplifiers optimized for low noise and designed to produce less than 50 mW output power are called

A) power amps.
B) medium-level amps.
C) video amps.
D) preamps.

Question 31

What op amp circuit has unity gain,maximum bandwidth and is the ideal interface to use between a high-impedance source and a low-impedance load?

A) voltage follower
B) comparator
C) mixer
D) diff amp

Question 32

What is the op amp circuit used when it is necessary to combine two or more analog signals into a single output?

A) voltage follower
B) comparator
C) summing amp
D) diff amp

Question 33

What op amp circuit is typically used to combine audio signals in a high-fidelity audio system?

A) voltage follower
B) comparator
C) mixer
D) diff amp

Question 34

The voltage gain produced when there is a feedback path between the output and the input is called the

A) open-loop voltage gain.
B) closed-loop voltage gain.
C) feedback voltage gain.
D) output voltage gain.

Question 35

An IC amplifier that has a flat response over a very broad range of frequencies and finds applications in such instruments as oscilloscopes,copiers,and scanners is the

A) power amp.
B) medium-level amp.
C) video amp.
D) preamp.

Question 36

What is the term used to describe the action of an op amp when,for example,the noninverting input voltage increases,the inverting input voltage immediately increases to the same value?

A) virtual ground
B) mixing
C) multiplexing
D) bootstrapping

Question 37

Many manufacturers' data sheets refer to the unity-gain frequency as the

A) gain-bandwidth product.
B) frequency of one.
C) gain of one.
D) cutoff.

Question 38

What type of op amp incorporates JFETs and bipolar transistors on the same chip?

A) BIFET
B) JBJT
C) BIMOS
D) BJTFET

Question 39

Op amps designed with minimum imperfections and intended for applications such as measurement and control are referred to as

A) accurate op amps.
B) precision op amps.
C) control op amps.
D) minimum op amps

Question 40

When no feedback path or loop is used,the voltage gain of an op amp is ________.

A) one
B) less than 100
C) maximum
D) 1000

Question 41

Unity-gain frequency is the frequency at which the voltage gain equals ________.

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

Question 42

What is the advantage of using external compensation for an op amp?

A) designer has more control over the high-frequency performance.
B) designer has more control over the low-frequency performance.
C) designer has more control over the voltage gain.
D) designer has more control over input impedance.

Question 43

The 741C op amp has an open-loop voltage gain of ________.

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

Question 44

What is very popular in integrated circuits because it is easier and less expensive to fabricate transistors on a chip than it is to fabricate resistors?

A) surface mounting.
B) nulling.
C) active loading.
D) bootstrapping.

Question 45

The maximum output current the op amp can produce is called the

A) maximum output current.
B) open-circuit output current.
C) short-circuit output current.
D) open-loop output current.

Question 46

The best method to eliminate output error and minimize thermal drift of an op amp is by

A) connecting a compensating capacitor.
B) using a nulling circuit.
C) using a tuned amplifier.
D) using a RLC filter.

Question 47

The voltage gains and bandwidths of IC video amps can be adjusted by connecting

A) compensating capacitors.
B) virtual grounds.
C) tunnel diodes.
D) different external resistors.

Question 48

Which op amp is the least expensive and most widely used?

A) 741A
B) 741N
C) 741E
D) 741C

Question 49

What is the CMRR of a 741C op amp at low frequencies?

A) 9 dB
B) 90 dB
C) 900 dB
D) 9000 dB

Question 50

What is added to some op amps in order to prevent oscillations?

A) external compensating capacitor.
B) external zener diode.
C) external potentiometer.
D) external constant current source.