5-Bit Successive Approximation ADC

A 5-bit successive approximation ADC using a 5-bit up-down counter as a successive approximation register and internal DAC. The analogue voltage comparator compares the input voltage to the output of the internal DAC and outputs the comparison to the successive approximation register. In this implementation, the register begins a binary search (counting up or down depending on the comparison) directed by the comparator and hones in on the input voltage. The obvious advantage of this setup over a flash ADC of similar resolution is it's size. A 5-bit flash ADC would require 31 comparators while a 6-bit ADC would require 63 comparators. Upgrading a successive approximation ADC only requires an additional flip-flop for each additional bit. It takes about a minute to converge and begin tracking. Be patient.

published 9 years ago