Bus Stuttering Encoder

Abstract

It was shown in Chapter 13 that the performance of an off-chip bus could be increased by avoiding a subset of patterns which resulted in noise greater than a specified limit. By eliminating the patterns that create the greatest amount of noise, the remaining patterns can be transmitted at a faster per-pin datarate without exceeding the user-defined noise limits of the system. The bus expansion encoding technique was successful in increasing the overall throughput of the bus even after considering the encoder overhead. The bus expansion encoder is ideal for applications where additional signal pins on the package are available for use when encoding the on-chip vectors; however, in the case where the number of package signal pins equals the on-chip bus width, then a different approach can be used.