Online clock routing in Xilinx FPGAs for high-performance and reliability

In this paper, we report the design and implementation of a reconfigurable system that exploits regional clocking resources that exist in Xilinx Virtex-4 FPGAs for increased performance and, for the first time, enhanced reliability. Unlike previous approaches, our system is able to individually manage the regional clock buffers (BUFRs) to adjust the frequency delivered to each hardware task and to detect and recover from faults affecting the clock-tree on-the-fly. Towards this end, we propose global and regional clock multiplexers, named GCMUX and RCMUX respectively, which allow for switching to spare clocking resources whenever needed. These multiplexers are based on the inner programmable interconnection points of the FPGA, leading to zero area overheads.