Using FPGAs to prototype a self-timed floating point co-processor

Self-timed circuits offer advantages over their synchronously clocked counterparts in a number of situations. However, self-timed design techniques are not widely used at present for a variety of reasons. One reason for the lack of experimentation with self-timed systems is the lack of commercially available parts to support this style of design. Field programmable gate arrays (FPGAs) offer an excellent alternative for the rapid development of novel system designs provided suitable circuit structures can be implemented. This paper describes a self-timed floating point co-processor built using a combination of Actel FPGAs and semi-custom CMOS chips. This co-processor implements IEEE standard single-precision floating point operations on 32-bit values. The control is completely self-timed. Data moves between parts of the circuit according to local constraints only: there is no global clock or global control circuit