Digital Electronics-Interfacing to the Analog World
Digital Electronics-Interfacing to the Analog World
21. Which of the following characterizes an analog quantity?
- Discrete levels represent changes in a quantity.
- Its values follow a logarithmic curve.
- It can be described with a finite number of steps.
- It has a continuous set of values over a given range.
22. A 4-bit stairstep-ramp A/D converter has a clock frequency of 100 kHz and maximum input voltage of 10 V.
- The maximum number of samples per second will be 6250.
- The maximum sample rate will be 100,000 samples/second.
- The minimum sample rate will be 6250 samples/second.
- The minimum sample rate will be 100,000 samples/second.
23. What is the accuracy of a D/A converter?
- It is the reciprocal of the number of discrete steps in the D/A output.
- It is the comparison between the actual output of the converter and its expected output.
- It is the converter's ability to resolve between forward and reverse steps when sequenced over its entire range of inputs.
- It is the deviation between the ideal straight-line output and the actual output of the converter.
24. 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?
- 0.111 V
- 1.17 V
- 0.109 V
- 0.857 V
25. Inaccurate A/D conversion may be due to:
- constant analog input voltage
- linear ramp usage
- intermittent counter inputs
- faulty sample-and-hold circuitry
27. What circuitry is on an ADC0808 IC?
- A multiplexer
- An ADC
- A 3-bit select input code
- All of the above
28. What is the maximum conversion time for an 8-bit successive-approximation ADC with a clock frequency of 20 kHz?
- 12.8 ms
- 6.4 ms
- 0.05 ms
- 0.4 ms
29. What is one advantage to using a parallel-encoded (flash) ADC?
- less expensive
- very fast conversion
- less complicated circuit
30. 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?
- 1
- 8
- 127
- 255