High-throughput asynchronous pipelines for fine-grain dynamic datapaths

Abstract

This paper introduces several new asynchronous pipeline designs which offer high throughput as well as low latency. The designs target dynamic datapaths, both dual-rail as well as single-rail. The new pipelines are latch-free and therefore are particularly well-suited for fine-grain pipelining, i.e., where each pipeline stage is only a single gate deep. The pipelines employ new control structures and protocols aimed at reducing the handshaking delay, the principal impediment to achieving high throughput in asynchronous pipelines. As a test vehicle, a 4-bit FIFO was designed using 0.6 micron technology. The results of careful HSPICE simulations of the FIFO designs are very encouraging. The dual-rail designs deliver a throughput of up to 860 million data items per second. This performance represents an improvement by a factor of 2 over a widely-used comparable approach by T.E. Williams (1991). The new single-rail designs deliver a throughput of up to 1208 million data items per second.