An apparatus including a set of one or more receivers; a first replica circuit being a substantial replica of at least a portion of one of the set of one or more receivers; a first control circuit generates an output signal selectively coupled to an input of the first replica circuit; a second replica circuit being a substantial replica of at least a portion of one of the set of one or more receivers; a comparator including a first input coupled to a first output of the first replica circuit, a second input coupled to a second output of the second replica circuit, and an output; and a second control circuit including an input coupled to the output of the comparator, and an output coupled to the first replica circuit and to the set of one or more receivers.