Fault Detection and Fault Diagnosis Techniques for Lookup Table FPGAs

In this paper, we present a novel fault detection and fault diagnosis technique for Field Programmable Gate Arrays (FPGAs). The cell is configured to implement a bijective function to simplify the testing of the whole cell array. The whole chip is partitioned into disjoint one-dimensional arrays of cells. For the lookup table (LUT), a fault may occur at the memory matrix, decoder, input or output lines. The input patterns can be easily generated with a k-bit binary counter, where k denotes the number of input lines of a configurable logic block (CLB). Theoretical proofs show that the resulting fault coverage is 100%. According to the characteristics of the bijective cell function, a novel built-in self-test structure is also proposed. Our BIST approaches have the advantages of requiring less hardware resources for test pattern generation and output response analysis. To locate a faulty CLB, two diagnosis sessions are required. However, the maximum number of configurations is k + 4 for diagnosing a faulty CLB. The diagnosis complexity of our approach is also analyzed. Our results show that the time complexity is independent of the array size of the FPGA. In other words, we can make the FPGA array C-diagnosable.