Ternary Limited-Weight Codes and Quaternary Transition-Signaling for Low-Power Bus Encoding

This paper presents a new bus encoding scheme by ternary limited-weight codes (ternary LWC) and quaternary transition-signaling for low-power, high-performance data transmission. In this technique, digit `0' indicates no transition, whereas `1' and `2' indicate two different types of transitions within a clock cycle. The number of ternary LWC code words as well as their length and weight affect the overall performance of the bus system. On the one hand, it is preferred to have fewer `1's and `2's in order to decrease the switching activity factor. On the other hand, shorter code words reduce the amount of redundancy. The mathematical analyses reveal that 64 4-digit ternary LWC code words with the maximum weight of three is the optimal solution, considering other criteria. Furthermore, our estimations show promising results, including 22.4% and 50.3% average reductions in switching activity and voltage swing, respectively. Therefore, the proposed bus encoding technique can reduce dynamic power up to 80.8%. In addition, it increases data transmission rate by the factor of 1.5.