Interfacing to the Analog World MCQs

Question 1

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

Accepted Answer

16

Answer

4

Answer

1/4

Answer

0.0625

Question 2

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

Accepted Answer

more complicated and more time consuming than the D/A conversion.

Answer

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

Answer

less complicated and less time consuming than the D/A conversion.

Answer

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

Question 3

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

Accepted Answer

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.

Answer

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.

Answer

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.

Answer

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.

Question 4

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

Accepted Answer

16 different values of voltage or current that are proportional to the input binary number

Answer

16 different values of voltage or current that are not proportional to the input binary number

Answer

32 different values of voltage or current that are not proportional to the input binary number

Answer

32 different values of voltage or current that are proportional to the input binary number

Question 5

Which of the following characterizes an analog quantity?

Accepted Answer

It has a continuous set of values over a given range.

Answer

Discrete levels represent changes in a quantity.

Answer

Its values follow a logarithmic curve.

Answer

It can be described with a finite number of steps.

Question 6

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

Accepted Answer

The minimum sample rate will be 6250 samples/second.

Answer

The maximum number of samples per second will be 6250.

Answer

The maximum sample rate will be 100,000 samples/second.

Answer

The minimum sample rate will be 100,000 samples/second.

Question 7

What is the accuracy of a D/A converter?

Accepted Answer

It is the comparison between the actual output of the converter and its expected output.

Answer

It is the reciprocal of the number of discrete steps in the D/A output.

Answer

It is the converter's ability to resolve between forward and reverse steps when sequenced over its entire range of inputs.

Answer

It is the deviation between the ideal straight-line output and the actual output of the converter.

Question 8

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

Accepted Answer

Vout/Vin = –Rf/Rin

Answer

Vout = Vin/Av

Answer

Vout/Vin = Rout/Rin

Answer

Vin/Vout = Rout/Rin

Question 9

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?

Accepted Answer

0.111 V

Answer

1.17 V

Answer

0.109 V

Answer

0.857 V