Design and design automation of rectification logic for engineering change

In a later stage of a VLSI design, it is quite often to modify a design implementation to accommodate the new specification, design errors, or to meet design constraints. In addition to meet the design schedule for the new implementation, the reduction of the mask set have become very critical. In this paper, we propose a new method to add a programmable rectification module to reduce the mask cost and to improve the turn around time. When a modification is needed, one can program the rectification module to achieve the new implementation. The rectification module can be designed by one mask programmable gate array, or an embedded FPGA. To reduce the size needed for the rectification module, we also propose algorithms, which can intelligently select some internal signals of the old implementation to become pseudo primary inputs and primary outputs. Our experimental results are very encouraging.