Combinational Design Discrimination via Minterm Counting
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Solution Overview
Problem
Current methods for determining whether two combinational designs are functionally different are inefficient and often require computationally expensive steps to confirm equivalence, leading to unnecessary processing in ASIC design flows.
Innovation Solution
The use of minterm counting techniques, including ordinary minterm counting (OMC) and weighted minterm counting (WMC), to distinguish between combinational designs by converting them into suitable data representations and comparing their minterm counts, with provisions for handling 'don't care' specifications and exceptions such as output and input inversions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current methods for determining functional differences between combinational designs are used, then equivalence can be determined, but computational cost and processing time increase significantly
Solution Approach 1:
The patent segments the combinational design into multiple sub-designs and processes them in parallel using a field-programmable gate array (FPGA). By dividing the large-scale equivalence determination problem into smaller sub-problems that can be concurrently evaluated, the system achieves both accurate functional difference detection and reduced processing time, resolving the contradiction between measurement precision and time loss.
2Reliability
If comprehensive equivalence determination methods are applied, then functional differences are accurately identified, but computational resources and processing complexity increase
Solution Approach 1:
The patent introduces an intermediary FPGA-based processing system that acts as a mediator between the combinational designs and the equivalence determination logic. This intermediary device provides a dedicated hardware architecture for parallel processing, achieving reliable equivalence determination without requiring complex software-based computational resources, thus resolving the contradiction between reliability and device complexity.
3Measurement precision
If detailed minterm counting analysis is performed on all sub-designs, then functional similarities and differences are accurately identified, but processing overhead increases
Solution Approach 1:
The patent performs preliminary minterm counting analysis on combinational sub-designs before full equivalence determination. By pre-processing and analyzing the minterm counts of individual sub-designs, the system identifies obvious functional differences early in the process, allowing it to avoid more computationally intensive full equivalence analysis in cases where the result is already evident, thus improving productivity while maintaining measurement precision.
Data Source
AI summary
Ordinary minterm counting (OMC) and weighted minterm counting (WMC) are applied as combinational design discriminators to a pair of combinational designs D1 and D2. OMC assigns the same weight to each minterm, while WMC assigns a weight that can vary. For application of minterm counting, D1 and D2 can be converted into BDDs. The size of the BDDs can be reduced by assigning binary values to some of the input variables. If the minterm counts of D1 and are within a certain tolerance, then D1 and D2 cannot be distinguished. Even if D1 and D2 are determined to represent different functionalities, they may still be sufficiently related such that classification of them as differing functionalities is inappropriate. Each such test of relatedness, between a pair of designs D1 and D2, can be referred to as an “exception.” Minterm counting can also be applied when don't cares are part of a design specification. Exceptions can apply to such minterm counts.