A new taxonomy for reconfigurable prefix adders

While previous taxonomies for prefix adders have focused on the design space of such adders with fixed topologies (in terms of fanout, radix, logic depth, wiring tracks), our work considers the design space of reconfigurable prefix adders (with applications in fault-tolerant adder design) by introducing several new degrees of freedom in the design space. Fault tolerance in general requires redundancy, so we start with a redundant structure which is a superset of the entire family of prefix adders with fanout-of-2 and then prune the redundant structure accordingly for the defect-free initial state or for when defects occur. In addition to the traditional prefix adders (Kogge-Stone, Han-Carlson, Brent-Kung) our taxonomy proposes several new variations that are equivalent in performance and complexity to the traditional structures, yet can mask different sets of faults.