Performance Comparison of Asynchronous Adders

In asynchronous systems, average function delays principally govern overall throughput. This paper compares the performance of six adder designs with respect to their average delays. Our results show that asynchronous adders (32 or 64-bits) with a hybrid structure (e.g., carry-select adders) run 20-40% faster than simple ripple-carry adders. Hybrid adders also outperform high-cost, strictly synchronous conditional-sum adders. 1 Introduction In clocked digital systems, speed and throughput is typically limited by the worst case delays associated with the slowest module in the system. For asynchronous systems, however, system speed may be governed by actual executing delays of modules, rather than their calculated worst case delays, and improving predicted average delays of modules (even those which are not the slowest) may often improve performance. In general, more frequently used modules have greater influences on overall performance. Statistics presented in [7] show that in a protot..