An analog-to-digital converter comprising a minimal amount of circuitry
for conversion of an input analog signal to a series of digital bits. A
differential comparator is provided for generating digital values to
which the digital bits correspond. A pair of digital-to-analog converters
are provided for generating, via successive approximation, a differential
feedback analog signal based on bits previously generated by the
differential comparator. The analog-to-digital converter compares the
differential feedback analog signal to the input analog signal, and based
on the comparison generates a digital value that corresponds to a digital
bit. In the method of the invention, an analog signal is converted to a
digital value using the analog-to-digital converter, and a pair of
digital-to-analog converters each generate, via successive approximation,
a differential feedback analog signal that is applied to a differential
comparator for comparison to the input analog signal being digitized.