A complete technique that does not use any additional components for enhancing the yield of field-programmable logic arrays (FPLAs) is presented. In this approach, the inherent sparsity (absence of devices at crosspoints) of programmable logic arrays (PLAs) is utilized to mask certain types of manufacturing defects within the unprogrammed FPLAs, thus reclaiming chips which are otherwise discarded. Two categories of faults (called type 1 and type 2) are considered. Type-1 faults, which can be diagnosed a priori, are considered first. After diagnosing type 1 faults, the mask can be reconfigured around the faulty crosspoints. A streamlined bipartite matching algorithm is presented to enhance the speed of this reconfiguration. The uniqueness of the approach is that the programming of an FPLA is formulated as a graph theoretic problem for which a polynomial time solution exists. Type-2 faults in general cannot be diagnosed a priori. Therefore, a dynamic technique is presented for the repair of type-2 faults. Unused product lines of the FPLA are utilized for the repair. With a sufficient number of excess product lines, it is shown that a defective FPLA is guaranteed to be rendered usable. A probability measure for the usability of defective FPLA is obtained both with and without the implementation of this technique. Computer studies have shown that FPLAs with even a large number of defects can be successfully repaired, thereby increasing the yield.>

Two techniques are presented to increase the effective yield of field programmable logic arrays (FPLAs). In the first technique, a reconfiguration scheme is proposed to dynamically alter the product-term allocation of the mask PLA onto the product lines of the raw FPLA once a type-two fault is diagnosed. This technique does not require any extra product lines to obtain a usable destination FPLA. The second technique utilizes the often unused product lines within the FPLA. It is shown that once an error is detected during the programming procedure, a product line can always be desensitized from the rest of the FPLA. The intended product term is then simply reprogrammed onto one of the extra product lines.>