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Analog to Digital Conversion

The purpose of the analog to digital is to quantize the input signal from the sample and hold circuit to 2B discrete levels - where B is the number of bits of the analog to digital converter (ADC). The input voltage can range from 0 to Vref (or -Vref to +Vref for a bipolar ADC). What this means is that the voltage reference of the ADC is used to set the range of conversion of the ADC. For a monopolar ADC, a 0V input will cause the converter to output all zeros. If the input to the ADC is equal to or larger than tex2html_wrap_inline2018 then the converter will output all ones. For inputs between these two voltage levels, the ADC will output binary numbers corresponding to the signal level. For a bipolar ADC, the minimum input is tex2html_wrap_inline2064 not 0V.

Tim Stilson
Thu Oct 17 11:25:23 PDT 1996