English: Illustration of how a comparator works. The schematic diagram (left) shows a comparator A with a constant voltage V_REF equal to half the supply voltage V_CC/2 applied to its inverting input by a voltage divider consisting of the two resistors R, and a triangle wave V_IN applied to its noninverting input. The graph (right) shows the input and output waveforms. The output of the comparator V_OUT is in a high state (saturated) when V_IN > V_REF and zero when V_IN < V_REF. A comparator consists of a specialized high speed op amp.