Deck 20: Time Response of Reactive Circuits

Question 1

The main purpose of an instrumentation amplifier is to amplify common mode voltage.

Answer 1

False

Question 2

A voltage-to-current converter works by controlling current proportional to the input voltage.

Answer 2

True

Question 3

The voltage gain of an instrumentation amplifier is set with an external resistor.

Answer 3

True

Question 4

A basic isolation amplifier has two electrically isolated sections.

Question 5

Refer to Figure 20-1. Which of these circuits is known as an instrumentation amplifier?

A)(a)
B)(b)
C)(c)
D)(d)

Question 6

A peak detectorʹs output continually changes based on the input.

Question 7

Active limiting and clamping employs an amplifier circuit.

Question 8

A voltage-to-current converter has a JFET in the feedback loop.

Question 9

Most isolation amplifiers use transformer coupling for isolation.

Question 10

Refer to Figure 20-1. Which of these circuits is known as an isolation amplifier?

A)(a)
B)(b)
C)(c)
D)(d)

Question 11

The diode clamper circuit output is an ac signal that has a dc reference point of the peak voltage of
the ac.

Question 12

Refer to Figure 20-1 (a). If and the closed loop gain is 450, the value of the external gain-setting resistor RG is:

A)
B)
C)
D)none of the above.

Question 13

The OTA is a voltage-to-current amplifier.

Question 14

One of the key characteristics of an instrumentation amplifier is its low input impedance.

Question 15

OTA stands for operational transistor amplifier.

Question 16

A voltage limiter that limits both positive and negative peaks uses two zener diodes connected
anode to cathode.

Question 17

Refer to Figure 20-1. Which of these circuits is known as a constant-current source?

A)(a)
B)(b)
C)(c)
D)(d)

Question 18

The OTA has a ________ input impedance and a ________ CMRR.

A)low, low
B)high, low
C)low, high
D)high, high

Question 19

A basic instrumentation amplifier has three op-amps.

Question 20

An active clamping circuit negates the opposite polarity 0.7 V peak by using two diodes in series.

Question 21

An active limiter includes an op-amp which:

A)works better under loaded conditions.
B)keeps the circuit from oscillating.
C)increases the output voltage.
D)allows a reference level to be set.

Question 22

In the classic three op-amp instrumentation amplifier, the differential voltage gain is usually produced by the:

A)second stage.
B)output op amp.
C)mismatched resistors.
D)first stage.

Question 23

The output of a peak detector is always:

A)equal to the min value of the peak level received since the last reset pulse.
B)70.7% of input.
C)equal to the max value of the peak level received since the last reset pulse.
D)none of the above.

Question 24

An instrumentation amplifier has a high:

A)output impedance.
B)supply voltage.
C)CMRR.
D)power gain.

Question 25

The primary function of the oscillator in an isolation amplifier is to:

A)convert dc to low frequency ac.
B)rectify high frequency ac to dc.
C)convert dc to high frequency ac.
D)produce dual polarity dc voltages for the input to the demodulator.

Question 26

When using an OTA in a Schmitt-trigger configuration, the trigger points are controlled by:

A)
B)
C)
D)both A and B.

Question 27

In some respects an isolation amplifier is nothing more than an elaborate:

A)instrumentation amplifier.
B)op amp.
C)rectifier and filter.
D)both A and B

Question 28

Refer to Figure 20-2 (b). If the load current would be:

A)2.08 mA.
B)2.08 A.
C)208 A.
D)20.8 mA.

Question 29

Refer to Figure 20-2. Which of these circuits is known as a peak detector?

A)(a)
B)(b)
C)(c)
D)(d)

Question 30

The voltage gain of an OTA can be calculated using the formula:

A)
B)
C)
D)

Question 31

Refer to Figure 20-2. Which of these circuits is known as a voltage-to-current converter?

A)(a)
B)(b)
C)(c)
D)(d)

Question 32

Refer to Figure 20-1 (b). If the current thru the load Figure 20-2 would be:

A)227 μA.
B)227 mA.
C)22.7 mA.
D)22.7 μA.

Question 33

The input signal for an instrumentation amplifier usually comes from:

A)a transducer.
B)an inverting amplifier.
C)a wheatstone bridge.
D)a differential amplifier.

Question 34

Refer to Figure 20-2 (d). If the voltage gain would be:

A)62.5.
B)625.
C)6.25.
D)not enough information.

Question 35

Refer to Figure 20-2. Which of these circuits contains an OTA?

A)(a)
B)(b)
C)(c)
D)(d)

Question 36

If an operational transconductance amplifier (OTA) is used as a nonlinear mixer and an audio signal is mixed with an RF signal, the output will be a(n) ________ signal.

A)amplitude modulated (AM)
B)square wave
C)triangular wave
D)frequency modulated (FM)

Question 37

Two zener diodes are used in a limiter circuit to:

A)better regulate a power supply.
B)limit both positive and negative peaks.
C)reduce interelectrode capacitance at high frequencies.
D)none of the above

Question 38

A voltage-to-current converter is used in applications where itʹs necessary to have an output load current that is controlled by ________.

A)input voltage
B)input frequency
C)output resistance
D)input resistance

Question 39

Refer to Figure 20-1 (a). If the would be:

A)551.
B)560.
C)56.1.
D)5.61.

Question 40

Refer to Figure 20-2. Which of these circuits is known as a current-to-voltage converter?

A)(a)
B)(b)
C)(c)
D)(d)

Question 41

Which statement best differentiates between limiter and clamper circuits?

A)A limiter limits the both peaks of the output of a given signal, while the clamper limits only one.
B)A limiter sets the limit of the peak output of a given signal while the clamper establishes a dc reference level based on the peak output of the signal from which the ac signal will vary.
C)A limiter sets a dc reference voltage that the ac signal varies upon while the clamper limits the peak output.
D)none of the above

Question 42

How many op-amps does the basic instrumentation amplifier consist of?

A)2
B)3
C)4
D)5

Question 43

An instrumentation amp with one open input:

A)may work correctly in a low noise environment.
B)will not work at all.
C)will allow common-mode noise to be present on the output.
D)both A and C

Question 44

Which op-amp circuit would be useful to switch to an ʺonʺ condition at a specified voltage?

A)instrumentation amp
B)isolation amplifier
C)operational transconductance amplifier configured as a Schmitt-trigger
D)voltage-to-current converter

Question 45

Which statement best describes the action of an OTA amplitude modulator?

A)The power supply bias adjusts the output level.
B)Variations of light intensity adjust the gain of the amplifier.
C)The variations of voltages applied to the current bias input adjusts the gain of the amplifier.
D)The OTA is versatile and can be configured to work in any of these ways.