A unified transformational approach for reductions in fault vulnerability, power, and crosstalk noise & delay on processor buses

In this paper we propose a coding scheme for general-purpose applications that can reduce power dissipation, crosstalk noise and crosstalk delay on the bus lines while simultaneously detecting errors at run time. The reduction in power dissipation can be achieved through reducing the bus switching activity. Not only is the switching activity in individual lines reduced but so is the coupling activity across the adjacent lines, the major contributor to the overall power dissipation in deep submicron technology. Detailed analysis of crosstalk noise and delay shows that eliminating certain patterns of transitions and reducing the infeasible ones in terms of crosstalk noise and power dissipation is a feasible strategy for alleviating these problems. We propose an encoding technique consisting of the use of predefined patterns of transitions, one for each possible combination of input data, to generate the codewords. The restriction to the predefined patterns of transitions enables fast encoding and low hardware overhead. This work presents an extensive analysis of the consequent reduction in crosstalk and power. SPICE derived experimental results show a reduction in worst case crosstalk delay and noise, ranging up to 24% and 10% respectively. Extensive experimental results for various applications show significant reduction in power dissipation ranging up to 44% for switching activity on the bus lines and up to 25% for coupling activity. The results also show a drastic reduction ranging up to 98% in the number of patterns that are most likely to produce crosstalk errors.