Analog-to-Digital ConversionThis is a sample of the large number of analog-to-digital conversion methods. The basic principle of operation is to use the comparator principle to determine whether or not to turn on a particular bit of the binary number output. It is typical for an ADC to use a digital-to-analog converter (DAC) to determine one of the inputs to the comparator.
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Index Electronics concepts Digital Circuits | |||
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Digital Ramp ADCConversion from analog to digital form inherently involves comparator action where the value of the analog voltage at some point in time is compared with some standard. A common way to do that is to apply the analog voltage to one terminal of a comparator and trigger a binary counter which drives a DAC. The output of the DAC is applied to the other terminal of the comparator. Since the output of the DAC is increasing with the counter, it will trigger the comparator at some point when its voltage exceeds the analog input. The transition of the comparator stops the binary counter, which at that point holds the digital value corresponding to the analog voltage.
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Index Electronics concepts Digital Circuits Reference Tocci Digital Systems, Sec 10-8. | ||
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Successive Approximation ADCIllustration of 4-bit SAC with 1 volt step size (after Tocci, Digital Systems).
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Index Electronics concepts Digital Circuits Reference Tocci Digital Systems, Sec 10-10. | |||||
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Index Electronics concepts Digital Circuits Reference Tocci Digital Systems, Sec 10-11. | |||
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