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Interfacing to the Analog World MCQ Questions & Answers

Interfacing to the Analog World MCQs : This section focuses on the "Interfacing to the Analog World". These Multiple Choice Questions (MCQs) should be practiced to improve the Interfacing to the Analog World skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.




Question 1

A 4-bit R/2R D/A converter has a reference of 5 V. What is the analog output for the input code 0101?

A. 3.125 V
B. 0.3125 V
C. 0.78125 V
D. –3.125 V

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Question 2

An analog-to-digital converter has a four-bit output. How many analog values can it represent?

A. 4
B. 01-Apr
C. 16
D. 0.0625

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Question 3

If an analog signal is to be converted to an 8-bit resolution, how many comparators are used in a parallel-encoded ADC?

A. 127
B. 128
C. 255
D. 256

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Question 4

Which of the equations below expresses the voltage gain relationship for an operational amplifier?

A. Vout = Vin/Av
B. Vout/Vin = Rout/Rin
C. Vin/Vout = Rout/Rin
D. Vout/Vin = –Rf/Rin

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Question 5

What is the acquisition time of the AD1154 sample-and-hold IC?

A. 1.5 s
B. 2.5 s
C. 3.5 s
D. 4.5 s

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Question 6

The quantization error in an analog-to-digital converter can be reduced by:

A. increasing the number of bits in the counter and DAC.
B. decreasing the number of bits in the counter and increasing the number of bits in the DAC.
C. increasing the number of bits in the counter and decreasing the number of bits in the DAC.
D. decreasing the number of bits in the counter and DAC.

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Question 7

One disadvantage of the tracking A/D converter is:

A. that it requires two counters—one for up and one for down.
B. that the binary output will oscillate between two binary states when the analog input is constant.
C. the need for an accurate clock reference for the counter.
D. the need for a latch and its associated control circuit.

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Question 8

What is the major advantage of the R/2R ladder DAC as compared to a binary-weighted-input DAC?

A. It has fewer parts for the same number of inputs.
B. It is much easier to analyze its operation.
C. It uses only two different resistor values.
D. The virtual ground is eliminated and the circuit is therefore easier to understand and troubleshoot.

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Question 9

How many different voltages can be output from a DAC with a 6-bit resolution?

A. 6
B. 16
C. 32
D. 64

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Question 10

What circuitry is on an ADC0808 IC?

A. A multiplexer
B. An ADC
C. A 3-bit select input code
D. All of the above

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Question 11

________ are the most linear of all the temperature transducers.

A. Thermistors
B. Thermocouples
C. IC temperature sensors
D. Resistance temperature detectors

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Question 12

What is the main disadvantage of the stairstep-ramp A/D converter?

A. The counter must count up from zero at the beginning of each conversion sequence, and the conversion time will vary depending on the input voltage.
B. It requires a counter.
C. It requires a precision clock in order for the conversion to be reliable.
D. All of the above

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Question 13

When comparing the conversions from digital-to-analog and analog-to-digital, the A/D conversion is generally:

A. less complicated but more time consuming than the D/A conversion.
B. more complicated and more time consuming than the D/A conversion.
C. less complicated and less time consuming than the D/A conversion.
D. more complicated but less time consuming than the D/A conversion.

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Question 14

Why is a binary-weighted DAC usually limited to 4-bit binary conversion?

A. too many pins on the IC
B. too many op amps needed
C. too many different values of capacitors
D. too many different values of resistors

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Question 15

The basic approach to testing D/A converters is to:

A. apply a sequence of binary codes covering the full range of input values to the circuit input while observing the output on an oscilloscope. The output should consist of a linear stairstep ramp.
B. single-step the device through its full input range while checking the output with a DMM.
C. check the output with zero input and then full input. The output of the converter should extend from zero to its maximum value. If so, then everything in between can be assumed to be operating properly.
D. apply the correct input to the analog terminal and then check to see if the proper binary code exists on the digital inputs.

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Question 16

Three characteristics of op amps make them almost ideal amplifiers: very high input impedance, very low impedance, and ________.

A. very high voltage gain
B. unlimited bandwidth
C. a low slew rate
D. very high current gain

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Question 17

Describe offset error for a DAC.

A. missing codes
B. error in the slope of the output staircase waveform
C. more or less input voltage is required for the first step than what is specified

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Question 18

What is the maximum conversion time for an 8-bit successive-approximation ADC with a clock frequency of 20 kHz?

A. 12.8 ms
B. 6.4 ms
C. 0.05 ms
D. 0.4 ms

View Answer

Question 19

Which of the statements below best describes the basic operation of a dual-slope A/D converter?

A. The input voltage is used to set the frequency of a voltage-controlled oscillator (VCO). The VCO quits changing frequency when the input voltage stabilizes. The frequency of the VCO, which is proportional to the analog input voltage, is measured and is displayed on the digital display as a voltage reading.
B. A ramp generator is used to enable a counter through a comparator. When the ramp voltage equals the input voltage, the counter is latched and then reset. The counter reading is proportional to the input voltage since the ramp is changing at a constant V/second rate.
C. A ramp voltage and analog input voltage are applied to a comparator. As the input voltage causes the integrating capacitor to charge, it will at some point equal the ramp voltage. The ramp voltage is measured and displayed on the digital panel meter.
D. Two ramps are generated: one by the input voltage and the other by a reference voltage. The input voltage ramp charges the integrating capacitor, while the reference voltage discharges the capacitor and enables the counter until the capacitor is discharged, at which time the counter value is loaded into the output latches.

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Question 20

What is the accuracy of a D/A converter?

A. It is the reciprocal of the number of discrete steps in the D/A output.
B. It is the comparison between the actual output of the converter and its expected output.
C. It is the converter's ability to resolve between forward and reverse steps when sequenced over its entire range of inputs.
D. It is the deviation between the ideal straight-line output and the actual output of the converter.

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Question 21

An analog quantity varies from 0–7 V and is input to a 6-bit A/D converter. What analog value is represented by each step on the digital output?

A. 0.111 V
B. 1.17 V
C. 0.109 V
D. 0.857 V

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Question 22

The main advantage of the successive-approximation A/D converter over the counter-ramp A/D converter is its:

A. more complex circuitry
B. less complex circuitry
C. longer conversion time
D. shorter conversion time

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Question 23

Which of the following describes the basic operation of a single-slope A/D converter.

A. The input voltage is used to set the frequency of a voltage-controlled oscillator (VCO). The VCO quits changing frequency when the input voltage stabilizes. The frequency of the VCO, which is proportional to the analog input voltage, is measured and is displayed on the digital display as a voltage reading.
B. A ramp generator is used to enable a counter through a comparator. When the ramp voltage equals the input voltage the counter is latched and then reset. The counter reading is proportional to the input voltage since the ramp is changing at a constant V/second rate.
C. A ramp voltage and analog input voltage are applied to a comparator. As the input voltage causes the integrating capacitor to charge, it will at some point equal the ramp voltage. The ramp voltage is measured and displayed on the digital panel meter.
D. Any of the above could be correct, depending on the specific type of A/D converter involved.

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Question 24

What is the speed of the up/down digital-ramp ADC (tracking ADC)?

A. 20 s
B. 10 s
C. 1 s
D. Relatively slow

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Question 25

What is the linearity of a D/A converter?

A. It is the reciprocal of the number of discrete steps in the D/A output.
B. It is the comparison between the actual output of the converter and its expected output.
C. It is the converter's ability to resolve between forward and reverse steps when sequenced over its entire range of inputs.
D. It is the deviation between the ideal straight-line output and the actual output of the converter.

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Question 26

The process by which a computer acquires digitized analog data is referred to as ________.

A. data acquisition
B. monotonicity
C. analog resolution
D. systematic digital conversion

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Question 27

What is the disadvantage to using a counter-ramp type ADC?

A. complex circuit
B. high cost
C. very slow

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Question 28

What is the resolution of a D/A converter?

A. the comparison between the actual output of the converter and its expected output
B. the reciprocal of the number of discrete steps in the D/A output
C. the deviation between the ideal straight-line output and the actual output of the converter
D. the ability to resolve between forward and reverse steps when sequenced over its entire range

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Question 29

What is the purpose of a sample-and-hold circuit?

A. To keep temporary memory
B. To hold a voltage constant so an ADC has time to produce an output
C. To hold a voltage constant so a DAC has time to produce an output
D. To hold data after a multiplexer has selected an output

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Question 30

An actuator is usually a device that:

A. converts analog data to meaningful digital data.
B. controls a physical variable.
C. stores digital data and then processes that data according to a set of specified instructions.
D. converts a physical variable to an electrical variable.

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Question 31

What is the conversion time of a flash converter?

A. 20 s
B. 10 s
C. 1 s
D. The conversion takes place continuously.

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Question 32

What is the resolution, in percent, of a 12-bit DAC?

A. 8.33
B. 0.049
C. 0.000488
D. 0.083

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Question 33

A 4-bit stairstep-ramp A/D converter has a clock frequency of 100 kHz and maximum input voltage of 10 V.

A. The maximum number of samples per second will be 6250.
B. The maximum sample rate will be 100,000 samples/second.
C. The minimum sample rate will be 6250 samples/second.
D. The minimum sample rate will be 100,000 samples/second.

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Question 34

If the same analog signal is to be converted to an 8-bit resolution using a counter-ramp ADC, how many comparator circuits would be used?

A. 1
B. 8
C. 127
D. 255

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Question 35

Inaccurate A/D conversion may be due to:

A. constant analog input voltage
B. linear ramp usage
C. intermittent counter inputs
D. faulty sample-and-hold circuitry

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Question 36

Which of the following characterizes an analog quantity?

A. Discrete levels represent changes in a quantity.
B. Its values follow a logarithmic response curve.
C. It can be described with a finite number of steps.
D. It has a continuous set of values over a given range.

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Question 37

What is the main disadvantage of the counter-ramp A/D converter?

A. It requires a counter.
B. The counter must count up from zero at the beginning of each conversion sequence, and the conversion time will vary depending on the input voltage.
C. It requires a precision clock in order for the conversion to be reliable.
D. The counter must count up from zero at the beginning of each conversion sequence, and the conversion time will vary depending on the input voltage. It requires a precision clock in order for the conversion to be reliable.

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Question 38

A transducer is a device that:

A. converts a physical variable to an electrical variable
B. converts analog data to meaningful data
C. controls a physical variable
D. stores digital data and then processes that data according to a set of specified instructions

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Question 39

A certain digital-to-analog converter has a step size of 0.25 V and a full-scale output of 7.75 V. Determine the percent of resolution and the number of input binary bits.

A. 31%, 4 bits
B. 3.23%, 4 bits
C. 31%, 5 bits
D. 3.23%, 5 bits

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Question 40

If the range of output voltage of a 6-bit DAC is 0 to 15 volts, what is the step voltage of the output?

A. 0.117 volt/step
B. 0.234 volt/step
C. 2.13 volts/step
D. 4.26 volts/step

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Question 41

What is the resolution of a D/A converter?

A. It is the reciprocal of the number of discrete steps in the D/A output.
B. It is the comparison between the actual output of the converter and its expected output.
C. It is the deviation between the ideal straight-line output and the actual output of the converter.
D. It is the converter's ability to resolve between forward and reverse steps when sequenced over its entire range of inputs.

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Question 42

What is one advantage to using a parallel-encoded (flash) ADC?

A. less expensive
B. very fast conversion
C. less complicated circuit

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Question 43

The output of a basic 4-bit input digital-to-analog converter would be capable of outputting:

A. 16 different values of voltage or current that are not proportional to the input binary number
B. 16 different values of voltage or current that are proportional to the input binary number
C. 32 different values of voltage or current that are not proportional to the input binary number
D. 32 different values of voltage or current that are proportional to the input binary number

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Question 44

Which of the following characterizes an analog quantity?

A. Discrete levels represent changes in a quantity.
B. Its values follow a logarithmic curve.
C. It can be described with a finite number of steps.
D. It has a continuous set of values over a given range.

View Answer

Question 45

What is gain error in a DAC?

A. missing codes
B. error in the slope of the output staircase waveform
C. more or less input voltage is required for the first step than what is specified

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Question 46

One major difference between a counter-ramp A/D converter and a successive-approximation converter is:

A. the counter-ramp A/D converter is much faster than the successive-approximation converter
B. with the successive-approximation converter the final binary result is always slightly less than the equivalent analog input, whereas with the counter-ramp A/D converter it is slightly more
C. with the successive-approximation converter the final binary result is always slightly more than the equivalent analog input, whereas with the counter-ramp A/D converter it is slightly less
D. none of the above

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Question 47

The primary disadvantage of the simultaneous A/D converter is:

A. that it requires the input voltage to be applied to the inputs simultaneously
B. the long conversion time required
C. the large number of output lines required to simultaneously decode the input voltage
D. the large number of comparators required to represent a reasonable sized binary number

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Question 48

What is the major advantage of the R/2R ladder D/A converter as compared to a binary-weighted D/A converter?

A. It has fewer parts for the same number of inputs.
B. It is much easier to analyze its operation.
C. It uses only two different resistor values.
D. The virtual ground is eliminated and the circuit is therefore easier to understand and troubleshoot.

View Answer

Question 49

What is the maximum conversion time for a counter-ramp ADC with 8-bit resolution and a clock frequency of 20 kHz?

A. 12.8 ms
B. 6.4 ms
C. 0.05 ms
D. 0.4 ms

View Answer

Question 50

Sample-and-hold circuits in A/D converters are designed to:

A. sample and hold the output of the binary counter during the conversion process
B. stabilize the comparator's threshold voltage during the conversion process
C. stabilize the input analog signal during the conversion process
D. sample and hold the D/A converter staircase waveform during the conversion process

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Question 51

A simultaneous A/D converter is also known as a(n) ________ A/D converter.

A. flash
B. synchronous
C. comparator
D. asynchronous

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Question 52

Two principal advantages of the dual-slope ADC are its:

A. high speed and low cost.
B. high sensitivity to noise and low cost.
C. low sensitivity to noise and high speed.
D. low sensitivity to noise and low cost.

View Answer