Pausible clocking-based heterogeneous systems

This paper describes a novel communication scheme, which is guaranteed to be free of synchronization failures, amongst multiple synchronous and asynchronous modules operating independently. In this scheme, communication between every pair of modules is done through an asynchronous FIFO channel; communication between a module and the FIFO is done using a request/acknowledge handshaking. Synchronization of handshake signals to the local module clock is done in an unconventional way [1], [2], [3], [4] — the local clock built out of a ring oscillator is paused or stretched, if necessary, to ensure that the handshake signal satisfies setup and hold time constraints with respect to the local clock. In order to validate this scheme, we implemented a test chip in 0.5μm CMOS. This chip is designed as a ring, composed of two synchronous modules, an asynchronous module, and two asynchronous FIFO’s. Each module functions as a receiver to one module and a sender to another module. Test results show that the chip functions reliably up to 456MHz. Keywords— Globally asynchronous locally synchronous, Stretchable clock, Synchronization, Heterogeneous systems