Asynchronous pipeline circuits

Patent Granted Asynchronous pipelines are used in asynchronous circuits, and have their pipeline registers clocked asynchronously. Generally speaking, they use a request/acknowledge system, wherein each stage can detect when it's "finished". When a stage is finished and the next stage has sent it a "request" signal, the stage sends an "acknowledge" signal to the next stage, and a "request" signal to the previous stage. When a stage receives an "acknowledge" signal, it clocks its input registers, thus reading in the data from the previous stage.