A FIFO Data Switch Design Experiment

A core problem in many pipelined circuit designs is data-dependent data flow. We describe a methodology and a set of circuit modules to address this problem in the asynchronous domain. We call our methodology P**3, or “P cubed.” Items flowing through a set of FIFO datapaths can be conditionally steered under the control of data carried by other FIFOs. We have used the P**3 methodology to design and implement a FIFO test chip that uses a data-dependent switch to delete marked data items conditionally. The circuit uses two on-chip FIFO rings as high-speed data sources. It was fabricated through MOSIS using their 0.6μ CMOS design rules. The peak data switch throughput was measured to be a minimum of 580 million data items per second at nominal Vdd of 3.3V.