Bridging Clock Domains by Synchronizing the Mice in the Mousetrap

We present the design of a first-in first-out buffer that can be used to bridge clock domains in GALS (Globally Asynchronous, Locally Synchronous) systems. Both the input and output side of the buffer have an independently clocked interface. The design of these kind of buffers inherently poses the problems of metastability and synchronization failure. In the proposed design the probability of synchronization failure can be decreased exponentially by increasing the buffer size. Consequently, at system level one can trade off between safety and low latency. The design is based on two well-known ideas: pipeline synchronization and mousetrap buffers. We first combine both ideas and then in several steps improve the design.