Multiwire Phase Encoding: A Signaling Strategy for High-Bandwidth, Low-Power Data Movement

Abstract

This article presents multiwire phase encoding (MWPE), a transition signaling technique aimed at chip-to-chip communication on silicon interposer technology, where multiple, relatively low-bandwidth transmission lines can be easily routed between high-performance dies. The encoding exploits timing correlation between transitions on multiple band-limited wires to achieve high ensemble bandwidth, potentially exceeding that of parallel conventionally encoded NRZ links. The unambiguous encoding enables instantaneous bit synchronization, resulting in low-power, low-latency, PLL-/DLL-free on-chip data movement. Theoretical and practical bandwidths achievable by phase-encoded links are evaluated as a function of channel properties. Link timing, driver, and receiver circuits are implemented to evaluate the link performance and power costs associated with moving MWPE data. The Hspice simulation-based estimates indicate that a 2-mm-long MWPE link can achieve 126-Gb/s bandwidth on a lossy, dispersive transmission line medium, with an energy cost of 0.24 pJ/bit in 22-nm FDX technology.