Digital Electronics: Principles, Devices and Applications

522 Digital ElectronicsMicrocomputerStart-Of-ConversionA/D ConverterEnd-of-ConversionDigital O/PClkINFigure 12.50A/D converter for data acquisition.Review Questions1. Briefly describe the process of digital-to-analogue conversion in a binary ladder network. How doesit differ from the simple resistive network used for the same purpose? Write an expression for theoutput analogue voltage for an n-bit binary ladder network.2. Briefly describe the resolution, accuracy, conversion time and monotonocity specifications of a D/Aconverter.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 arethe merits and demerits of this type of converter? How does the architecture of a flash converterdiffer 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 conventionalcounter-type A/D converter.7. Describe with the help of a schematic diagram the principle of operation of a successiveapproximation type A/D converter. Explain the sequence of operation of conversion of an analoguesignal 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-slopeintegrating-type A/D converter;(d) the use of a D/A converter as a digitally controlled voltage attenuator.