GALS at ETH Zurich: success or failure?

The Integrated Systems Laboratory (IIS) of ETH Zurich (Swiss Federal Institute of Technology) has been active in globally-asynchronous locally-synchronous (GALS) research since 1998. During this time, a number of GALS circuits have been fabricated and tested successfully on silicon. From a hardware designers point of view, this article summarizes the evolution from proof of concept designs over multi-point interconnects to applications that specifically take advantage of GALS operation to improve cryptographic security. In spite of the fact that they fail to address numerous idiosyncrasies of GALS (such as good partitioning into synchronous islands, port controller design, pausable clock generators, design for test, etc.), hierarchical design flows have been found to form a workable basis. What prevents GALS from gaining a wider acceptance mainly is the initial effort required to come up with a design flow that is efficient and dependable