522
Digital Electronics
Microcomputer
Start-Of-Conversion
A/D Converter
End-of-Conversion
Digital O/P
Clk
IN
Figure 12.50 A/D converter for data acquisition.
Review Questions
1. Briefly describe the process of digital-to-analogue conversion in a binary ladder network. How does
it differ from the simple resistive network used for the same purpose? Write an expression for the
output analogue voltage for an n-bit binary ladder network.
2. Briefly describe the resolution, accuracy, conversion time and monotonocity specifications of a D/A
converter.
3. Briefly describe the following with reference to D/A converters:
(a) a multiplying-type D/A converter;
(b) a companding-type D/A converter;
(c) the current steering mode of operation;
(d) the voltage switching mode of operation.
4. With reference to A/D converters, differentiate between:
(a) resolution and accuracy;
(b) nonlinearity (NL) and differential nonlinearity (DNL).
5. Briefly describe the principle of operation of a simultaneous or flash-type A/D converter. What are
the merits and demerits of this type of converter? How does the architecture of a flash converter
differ from that of a half-flash converter?
6. Describe with the help of a schematic diagram the operation of a tracking-type A/D converter.
Explain how it overcomes the inherent disadvantage of a longer conversion time of the conventional
counter-type A/D converter.
7. Describe with the help of a schematic diagram the principle of operation of a successive
approximation type A/D converter. Explain the sequence of operation of conversion of an analogue
signal to its digital equivalent when the expected digital output is 1010.
8. Explain the following:
(a) why a tracking type A/D converter is particularly suitable for fast-changing analogue signals;
(b) the use of a D/A converter as a programmable integrator;
(c) why a dual-slope integrating-type A/D converter has a higher accuracy than a single-slope
integrating-type A/D converter;
(d) the use of a D/A converter as a digitally controlled voltage attenuator.
Digital Electronics
Microcomputer
Start-Of-Conversion
A/D Converter
End-of-Conversion
Digital O/P
Clk
IN
Figure 12.50 A/D converter for data acquisition.
Review Questions
1. Briefly describe the process of digital-to-analogue conversion in a binary ladder network. How does
it differ from the simple resistive network used for the same purpose? Write an expression for the
output analogue voltage for an n-bit binary ladder network.
2. Briefly describe the resolution, accuracy, conversion time and monotonocity specifications of a D/A
converter.
3. Briefly describe the following with reference to D/A converters:
(a) a multiplying-type D/A converter;
(b) a companding-type D/A converter;
(c) the current steering mode of operation;
(d) the voltage switching mode of operation.
4. With reference to A/D converters, differentiate between:
(a) resolution and accuracy;
(b) nonlinearity (NL) and differential nonlinearity (DNL).
5. Briefly describe the principle of operation of a simultaneous or flash-type A/D converter. What are
the merits and demerits of this type of converter? How does the architecture of a flash converter
differ from that of a half-flash converter?
6. Describe with the help of a schematic diagram the operation of a tracking-type A/D converter.
Explain how it overcomes the inherent disadvantage of a longer conversion time of the conventional
counter-type A/D converter.
7. Describe with the help of a schematic diagram the principle of operation of a successive
approximation type A/D converter. Explain the sequence of operation of conversion of an analogue
signal to its digital equivalent when the expected digital output is 1010.
8. Explain the following:
(a) why a tracking type A/D converter is particularly suitable for fast-changing analogue signals;
(b) the use of a D/A converter as a programmable integrator;
(c) why a dual-slope integrating-type A/D converter has a higher accuracy than a single-slope
integrating-type A/D converter;
(d) the use of a D/A converter as a digitally controlled voltage attenuator.