Triple-modular redundancy is a form of spatial redundancy in which logic is replicated three times, and their outputs are compared in a comparator.

Triple-modular ensures that if a single-event upset hits one of the replicated elements, the other two unaffected elements, will override the erroneous value. A single-event upset on the voter itself can still affect the result, but given the small size of the voter, compared to the size of the elements that it is protecting, this reduces the vulnerable surface. If necessary, the voter itself can be made triply-redundant, or implemented using radiation hardened electronics.