For successive approximation in general, see Successive approximation. A successive approximation ADC is a type of sample and hold circuit pdf-to-digital converter that converts a continuous analog waveform into a discrete digital representation via a binary search through all possible quantization levels before finally converging upon a digital output for each conversion. A successive approximation register subcircuit designed to supply an approximate digital code of Vin to the internal DAC.
An internal reference DAC that, for comparison with VREF, supplies the comparator with an analog voltage equal to the digital code output of the SARin. Then the next bit is set to 1 and the same test is done, continuing this binary search until every bit in the SAR has been tested. An input voltage source Vin. A reference voltage source Vref to normalize the input.
A DAC to convert the ith approximation xi to a voltage. DAC’s voltage with the input voltage. Example: The ten steps to converting an analog input to 10 bit digital, using successive approximation, are shown here for all voltages from 5 V to 0 V in 0. Since the reference voltage is 5 V, when the input voltage is also 5 V all bits are set.
As the voltage is decreased to 4. 9 V, only some of the least significant bits are cleared. The MSB will remain set until the input is one half the reference voltage, 2.