In an asynchronous system, data dependency in the operation of a functional unit can be used to drastically reduce the average latency of the unit. Since asynchronous circuits operate correctly independent of delays, they are very robust to physical parameter variations. Temperature and voltage can be varied to adjust speed or power consumption. Asynchronous techniques can be used for low power design due to the absence of a global clock, the locality of activity, the automatic shut-off of inactive parts, and the absence of spurious transitions. A QDI circuit does not use any assumption on, or knowledge of, delays in operators and wires, with the exception of some forks, called isochronic forks , in which the delays on the different branches of the fork are assumed to be similar.
QDI circuits are the most conservative asynchronous circuits in terms of the use of delays.
But they are also the most robust to physical parameters variations because the circuit's dependence on delays is minimal. It is this robustness that makes it possible to exchange energy and throughput against each other through voltage adjustments. Another goal of this project is to show that delay assumptions are not necessary to achieve high performance in asynchronous circuits. To see some of the work done in the Caltech VLSI group, please visit the chips page.