Interfacing to the Analog World problems
- 1. A transducer is a device that:
Options- 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 Discuss
Correct Answer: converts a physical variable to an electrical variable
- 2. The basic approach to testing D/A converters is to:
Options- 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. Discuss
Correct Answer: 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.
- 3. Inaccurate A/D conversion may be due to:
Options- A. constant analog input voltage
- B. linear ramp usage
- C. intermittent counter inputs
- D. faulty sample-and-hold circuitry Discuss
Correct Answer: faulty sample-and-hold circuitry
- 4. What is the maximum conversion time for an 8-bit successive-approximation ADC with a clock frequency of 20 kHz?
Options- A. 12.8 ms
- B. 6.4 ms
- C. 0.05 ms
- D. 0.4 ms Discuss
Correct Answer: 0.4 ms
- 5. 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?
Options- A. The engineer is probably not using the correct data format for the specific instruments being used to collect the data.
- B. The GPIB cable is too long; a bus extender should be used.
- C. The cable should be shielded and properly grounded.
- D. The tests themselves probably produced extraneous signals that confused the instruments, resulting in unusable data. Discuss
Correct Answer: The GPIB cable is too long; a bus extender should be used.
- 6. If an analog signal is to be converted to an 8-bit resolution, how many comparators are used in a parallel-encoded ADC?
Options- A. 127
- B. 128
- C. 255
- D. 256 Discuss
Correct Answer: 256
- 7. What is one advantage to using a parallel-encoded (flash) ADC?
Options- A. less expensive
- B. very fast conversion
- C. less complicated circuit Discuss
Correct Answer: very fast conversion
- 8. ________ are the most linear of all the temperature transducers.
Options- A. Thermistors
- B. Thermocouples
- C. IC temperature sensors
- D. Resistance temperature detectors Discuss
Correct Answer: IC temperature sensors
- 9. Which of the equations below expresses the voltage gain relationship for an operational amplifier?
Options- A. Vout = Vin/Av
- B. Vout/Vin = Rout/Rin
- C. Vin/Vout = Rout/Rin
- D. Vout/Vin = ?Rf/Rin Discuss
Correct Answer: Vout/Vin = ?Rf/Rin
- 10. Three characteristics of op amps make them almost ideal amplifiers: very high input impedance, very low impedance, and ________.
Options- A. very high voltage gain
- B. unlimited bandwidth
- C. a low slew rate
- D. very high current gain Discuss
Correct Answer: very high voltage gain
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