A structured approach for routing of MCMs

Abstract

This paper presents a structured methodology for routing of multichip modules (MCMs) suitable for an EDA system that can guarantee 100% completion of routes irrespective of connection density. It uses a rather simple and straightforward modularized approach which, not only guarantees 100% completion of routes, but also optimizes and predetermines the number of layers required. This approach is structured using a Pre-sorter Module (PSM) and a Central Routing Adapter (CRA). Each chip or sub-module in an MCM will go through the PSM that re-arranges the node connection sequence by means of a horizontal-vertical matrix prior to the connection to the CRA. The CRA provides direct point-to-point connections based on the netlist for all chips or sub-modules in the MCM. The set of connections between the nodes of two chips (or sub-modules) is defined as a connection relationship. The number of connection relationships is n(n-1)/2, where n is the number of chips or sub-modules. By this approach, maximum number of layers in the CRA to route all connections among the chips or sub-modules will be (n-2). The design and development of these PSM and CRA are elaborated, and a 4-chip MCM example is used for illustration.