Page 383 - Op Amps Design, Applications, and Troubleshooting
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Review Questions 359
TABLE 8.4
Analog Input D/A Output Comparator Output
(Volts) SAR Status (Volts) (Volts)
5.7 1000 5.0 Low
5.7 1100 7.5 High
5.7 1010 6.25 High
5.7 1001 5.625 Low
D/A converter, can be implemented with software internal to a microprocessor.
However, the speed is generally much slower than a dedicated converter.
REVIEW QUESTIONS
1. A certain A/D converter has a 12-bit resolution specification for the analog input
range of 0 to 10 volts. What is the smallest voltage change that can be represented in
the output?
2. If the binary output of an A/D converter does not numerically increase with every
increase in input voltage, we say the converter is .
3. The total time required for an A/D converter to obtain a valid digital output for a
given analog input is called .
4. Contrast and explain the terms acquisition time and aperture time with reference to
sample-and-hold circuits.
5. Would a weighted D/A converter be the best choice for a 64-bit converter circuit?
Explain your answer.
6. What type of A/D conversion circuit provides the fastest conversion times? What are
its disadvantages?
7. If a certain successive approximation A/D converter requires 10 microseconds to
resolve a 0-volt to 2-volt step change on the input, how long will it take to resolve a
0-volt to 5-volt step change?
8. Repeat question 7 for a tracking A/D converter.
9. The use of a sample-and-hold circuit greatly reduces the highest usable frequency for
an A/D converter. (True or False)
10. Discuss the relationship between droop rate in a sample-and-hold circuit and the
necessary conversion time of a subsequent A/D converter circuit.