Deck 15: Differential Amplifiers

Question 1

The voltage gain of a differential amplifier divided by its common-mode voltage gain is referred to as the

A) input offset voltage.
B) common-mode rejection ratio.
C) differential output.
D) active load ratio.

Answer 1

B

Question 2

Base resistors can produce input error voltages when the two halves of the diff amp are not perfectly symmetrical.

Answer 2

True

Question 3

In order to get single-ended input operation using a diff amp,one of the inputs is used and the other input is grounded.

Answer 3

True

Question 4

If compensation of an op amp becomes necessary,the best approach is to use

A) nulling circuits.
B) filtering circuits.
C) squelching circuits.
D) regulating circuits.

Question 5

The input circuit used in most op amps is the common-collector amplifier.

Question 6

A differential amplifier output requires that the load is single-ended and has one end grounded.

Question 7

The input impedance of a diff amp is half as high as a single common-emitter amplifier.

Question 8

When the noninverting and inverting input voltages of a differential amp are present,the output voltage equals the voltage gain times the difference of the two input voltages.

Question 9

Components produced and connected during the manufacturing process on a small piece of semiconductor material are called

A) integrated circuits.
B) differential circuits.
C) CMOS.
D) discrete circuits.

Question 10

The term operational amplifier refers to an amplifier that performs a mathematical operation.

Question 11

A diff amp is sometimes called a long-tail pair because the two transistors share a common collector resistor.

Question 12

The input bias current of an op amp is defined as the sum of the dc base currents.

Question 13

With diff amp configurations,when a single-ended output is used,the input may be noninverting or inverting.

Question 14

The same input voltage that is applied to each base of a differential amplifier is called

A) complimentary signal.
B) nulling signal.
C) common-mode signal.
D) single-ended signal.

Question 15

The input offset voltage is defined as the input voltage that would produce the same output error voltage in a perfect diff amp.

Question 16

The typical op amp is a dc amplifier with very high gain,very high input impedance,and very low output impedance.

Question 17

The diff amp is extremely useful as the input stage of an op amp because

A) it has low input impedance.
B) it has a single-ended input.
C) it amplifies the common-mode signal.
D) it attenuates the common-mode signal.

Question 18

The three op amp data sheet characteristics that designers use when accurate answers are required are input bias current,input offset current,and input offset voltage.

Question 19

With diff amp configurations,the voltage gain is maximum when a single-ended output is used.

Question 20

The input offset current is defined as the difference of the dc base currents.

Question 21

What can produce input error voltages when the two halves of the diff amp are not perfectly symmetrical?

A) collector resistors
B) emitter resistors
C) base resistors
D) coupling capacitors

Question 22

In an op amp,the difference of the dc currents is called the

A) input offset current.
B) input bias current.
C) difference current.
D) dc mean current.

Question 23

Data sheet characteristics that designers use for accurate answers do not include

A) input bias current.
B) input offset current.
C) input offset resistance.
D) input offset voltage.

Question 24

The + symbol when used with an input of an op amp represents

A) the inverting input.
B) the noninverting input.
C) the differential input.
D) the single-ended input.

Question 25

Which of the following is not a characteristic of an op amp?

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

Question 26

When both the noninverting and inverting input voltages are present,the total input is called a

A) single-ended input.
B) noninverting input.
C) differential input.
D) complimentary input.

Question 27

The input impedance of a diff amp is

A) half as high as a single common-emitter stage.
B) twice as high as a single common-emitter stage.
C) the same as a single common-emitter stage.
D) four times as high as a single common-emitter stage.

Question 28

In order to get single-ended operation when using a diff amp

A) one input is used and the other is grounded.
B) one input is connected to the power supply and the other is grounded.
C) both inputs are used.
D) both inputs are grounded.

Question 29

The input circuit used in most op amps is the

A) preamp.
B) tuned RF amp.
C) common-collector.
D) differential amp.

Question 30

Because a diff amp shares a common emitter resistor,it is sometimes called

A) a sharing amp.
B) an emitter sharing amp.
C) a short-tail pair.
D) a long-tail pair.

Question 31

What are typically used as current sources and active loads in the design of IC op amps?

A) current limiters
B) zener regulators
C) current mirrors
D) current amps

Question 32

The most popular integrated circuits and the ICs manufactured with all components being part of one chip are called ________.

A) trivalent
B) pentavalent
C) duolithic
D) monolithic

Question 33

When two or more monolithic ICs are fabricated in one package,they are referred to as ________.

A) hybrid
B) thoroughbred
C) discrete
D) compensated

Question 34

When a single-ended output of a differential amplifier is used,the input is

A) inverting only.
B) noninverting only.
C) differential only.
D) either inverting or noninverting.

Question 35

Components that are easily fabricated on a chip do not include ________.

A) transistors
B) capacitors
C) diodes
D) resistors

Question 36

Which diff amp configuration produces the maximum voltage gain?

A) differential input with differential output
B) differential input with single-ended output
C) single-ended input with differential output
D) single-ended input with single-ended output

Question 37

In the manufacturing process of an IC,the procedure of sealing off the epitaxial layer with silicon dioxide is called ________,

A) compensation
B) sealation
C) passivation
D) crystallization

Question 38

In an op amp,the average of the dc base currents is referred to as

A) input offset current.
B) input bias current.
C) input average current.
D) base average current.

Question 39

An amplifier that performs a mathematical operation is referred to as

A) a math amp.
B) an op amp.
C) a calc amp.
D) a comp amp.

Question 40

The Intel P4 Prescott version microprocessor contains approximately

A) 125 transistors.
B) 125 thousand transistors.
C) 125 million transistors.
D) 125 billion transistors.

Question 41

When a diff amp is amplifying the wanted signal and discriminating against the common-mode signal the CMRR is

A) high.
B) low.
C) less than 1.
D) equal to the common-mode voltage gain divided by the voltage gain.

Question 42

Integrated circuits with fewer than 12 integrated components are referred to as

A) small-scale integration.
B) medium-scale integration.
C) large-scale integration.
D) very large scale integration.

Question 43

Ultra large scale integration refers to placing approximately how many components on a single chip?

A) 12 to 100
B) more than 100
C) thousands
D) more than a million

Question 44

When a differential amplifier is not perfectly symmetrical

A) there will be a small ac output voltage.
B) there will be no common-mode amplification.
C) there will be no ac output voltage.
D) there will be 0 V at the output.

Question 45

Data sheets generally specify common-mode rejection ratio in ________.

A) mhos
B) volts
C) decibels
D) joules

Question 46

What is the common-mode voltage gain for the circuit shown in Figure 15-21?

A) 1
B) 0.5
C) 1.5
D) 2

Question 47

What op amp data sheet characteristic is defined as the input voltage that would produce the same output error voltage in a perfect diff amp?

A) input difference voltage
B) input error voltage
C) input bias voltage
D) input offset voltage

Question 48

What is the type of IC that is manufactured with resistors and capacitors integrated,but transistors and diodes are connected as discrete components?

A) thin film or thick film
B) analog
C) digital
D) hybrid

Question 49

What is the output voltage for the circuit shown in Figure 15-21?

A) 15 mV
B) 1.5 mV
C) 0.5 mV
D) 0.5 V

Question 50

The formula used to convert the CMRR to decibels is

A) 10 log CMRR.
B) 20 log CMRR.
C) 30 log CMRR.
D) 40 log CMRR.