A quantization circuit includes a plurality of resistors, a plurality of
tap points, and a plurality of coarse comparators. Each coarse comparator
has a first input coupled to an input voltage and a second input coupled
to a corresponding coarse tap point voltage. Each coarse comparator
operates during a first phase to produce a "1" only if the input voltage
exceeds the corresponding coarse tap point voltage. A plurality of fine
comparators each have a first input coupled to the input voltage, and
each fine comparator operates during a second phase to produce a fine
output level indicative of whether the input voltage exceeds a
corresponding tap point voltage of a group of tap points located
immediately below the tap point connected to the highest coarse
comparator producing a "1".