A device includes a comparator, a reference signal node electrically coupled to a first input of the comparator, a plurality of test signal nodes, a plurality of first select signal nodes, a first multiplexer coupled between the plurality of test signal nodes and the comparator, a plurality of latches, a plurality of second select signal nodes, and a second multiplexer. Each first select signal node corresponds to a test signal node. The first multiplexer electrically couples one of the plurality of test signal nodes to a second input of the comparator in response to a corresponding first select signal. Each latch corresponds to a test signal node. Each second select signal node corresponds to a latch. The second multiplexer electrically couples the output of the comparator to an input of one of the plurality of latches in response to a corresponding second select signal.