UBC Theses and Dissertations
A novel interleaved and distributed FIFO Sood, Santosh
In deep submicron technologies, the delays of metal lines continue to increase in spite of an increasing number of metal layers and the use of low-k dielectrics. Thus, some form of interconnect pipelining is required in throughput intensive designs. Various approaches have been used for interconnect pipelining, e.g., synchronous, asynchronous, GALS and source-synchronous, and each presents a trade-off between the throughput and latency that can be achieved. This work provides an evaluation of the synchronous and the source-synchronous methods of interconnect pipelining. Reference designs for various synchronous and source-synchronous signalling methods are presented. The source-synchronous method entails the forwarding of a clock along with data; this forwarded clock suffers from skew due to process, voltage and temperature variations along the forwarded path. A FIFO is used to compensate for the skew between the forwarded clock and the local clock at the receiver end. We present a novel, interleaved and distributed FIFO that implements wave pipelining between the FIFO stages. This FIFO design helps to lower the latency of the source-synchronous interconnect. A metric of comparison called velocity is introduced, and a comparison of the performance of synchronous and source-synchronous signalling is presented on the metrics of throughput, velocity and power.
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