A die includes a plurality of through-substrate vias (TSVs) penetrating a substrate of the die, wherein the plurality of TSVs are grouped as a plurality of TSV pairs. A plurality of contact pads is coupled to the plurality of TSVs, wherein the plurality of contact pads is exposed on a first surface of the die. The die further includes a plurality of balanced pulse comparison units, wherein each of the plurality of balanced pulse comparison units includes a first input and a second input coupled to a first TSV and a second TSV of one of the plurality of TSV pairs. The die further includes a plurality of pulse latches, each including an input coupled to an output of one of the plurality of balanced pulse comparison units.