Interfacing to the Analog World MCQs

Question 1

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

Accepted Answer

3.5 s

Answer

1.5 s

Answer

2.5 s

Answer

4.5 s

Question 2

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

Accepted Answer

12.8 ms

Answer

6.4 ms

Answer

0.05 ms

Answer

0.4 ms

Question 3

A test system using the GPIB is being used to monitor a potentially dangerous crash test from a distance of 200 feet. The engineer decides to have you fabricate a special cable, rather than order one, since all the materials are on hand and the tests are already behind schedule. When the tests are run, the test system is erratic and the data is almost useless. What has gone wrong?

Accepted Answer

The GPIB cable is too long; a bus extender should be used.

Answer

The engineer is probably not using the correct data format for the specific instruments being used to collect the data.

Answer

The cable should be shielded and properly grounded.

Answer

The tests themselves probably produced extraneous signals that confused the instruments, resulting in unusable data.

Question 4

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

Accepted Answer

3.23%, 5 bits

Answer

31%, 4 bits

Answer

3.23%, 4 bits

Answer

31%, 5 bits

Question 5

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

Accepted Answer

flash

Answer

synchronous

Answer

comparator

Answer

asynchronous

Question 6

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

Accepted Answer

the large number of comparators required to represent a reasonable sized binary number

Answer

that it requires the input voltage to be applied to the inputs simultaneously

Answer

the long conversion time required

Answer

the large number of output lines required to simultaneously decode the input voltage

Question 7

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

Accepted Answer

very high voltage gain

Answer

unlimited bandwidth

Answer

a low slew rate

Answer

very high current gain

Question 8

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

Accepted Answer

stabilize the input analog signal during the conversion process

Answer

sample and hold the output of the binary counter during the conversion proces

Answer

stabilize the comparator's threshold voltage during the conversion process

Answer

sample and hold the D/A converter staircase waveform during the conversion process

Question 9

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

Accepted Answer

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.

Answer

It requires a counter.

Answer

It requires a precision clock in order for the conversion to be reliable.

Answer

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.