Q.What is an Analog to Digital convertor?

An analog-to-digital converter (ADC) performs the reverse of a DAC: it turns a continuous analog input voltage into an equivalent digital (binary) code, the essential first step in letting digital systems process real-world signals.

A widely taught design is the counting (or staircase) ADC, whose block diagram combines four parts: a comparator, a binary counter, a DAC, and a clock with control logic. It works by successive comparison in a feedback loop:

1. The counter starts at zero, and its output is fed to a DAC that converts it to an analog voltage.
2. The comparator compares this DAC output with the unknown analog input.
3. As long as the DAC voltage is below the input, the clock keeps incrementing the counter, so the DAC output rises step by step, producing a rising staircase waveform.
4. The moment the staircase just exceeds the analog input, the comparator changes state, stops the counter, and the counter's current value is the required digital output. …