Interconnect testing in cluster-based FPGA architectures

As IC densities are increasing, cluster-based FPGA architectures are becoming the architecture of choice for major FPGA manufacturers. A cluster-based architecture is one in which several logic blocks are grouped together into a coarse-grained logic block. While the high density local interconnect often found within clusters serves to improve FPGA utilization, it also greatly complicates the FPGA interconnect testing problem. To address this issue, we have developed a hierarchical approach to define a set of FPGA configurations which enable interconnect faults to be detected. This technique enables the detection of bridging faults involving intra-cluster interconnect and extra-cluster interconnect. The hierarchical structure of a cluster-based tile is exploited to define intra-cluster configurations separately from extra-cluster configurations, thereby improving the efficiency of the configuration definition process. By guaranteeing that both intra-cluster and extra-cluster configurations have several test transparency properties, hierarchical fault detectability is ensured.