LUT-based Circuit Approximation with Targeted Error Guarantees

Approximate circuits are widely gaining popularity in various fields where error tolerance is applicable. However, striking the right balance between error tolerance and the output quality is a challenging step in the overall design of approximate systems. We propose a systematic approach utilizing Look-Up Table (LUT)-based netlist transformations to achieve approximation while targeting specific error guarantees. Specifically, we employ a SAT-based property checking technique to accommodate worst-case error constraints acting as error guarantees. The proposed methodology involves the formulation of templates to enable the reusability of the technique for different design choices. The analysis comprises of fitness function evaluation based on layout area or the considered error guarantees. We analyze the impact of different parameters on the quality of the output of the resulting approximation and the time taken to obtain them.