Design of an asynchronous ACS for Viterbi decoder

In this paper, we present a new asynchronous ACS (adder-compare-select) unit, which is a key building block in the Viterbi decoder. Asynchronous self-timed control and DCVSL (Differential Cascade Voltage Switch Logic) have been used in the ACS unit. The simulation results show that the average case response time 3.51ns is only 42.6% the worst case response time 8.23ns. This explains that the asynchronous ACS unit has performance advantage over the synchronous one.