Design of testable multipliers for fixed-width data paths

The usage of multipliers in fixed-width data-dominated architectures (also termed data paths) poses serious testability problems. Due to truncation of their outputs, the fault observability of the multipliers degrades,and the resulting output patterns are inadequate to completely test functional blocks that are driven by them. Consequently, the overall random pattern testability of data paths deteriorates substantially. In this paper, we propose new generic design schemes, based on residue number system arithmetic, to improve the overall testability of data paths. The approach uses, in the test mode, the truncated least significant bits of the product to increase the variety of patterns at the output of a multiplier. This, in turn, improves the fault detectability of multipliers, and consequently, have a remarkable impact on the overall testability of data paths. The proposed techniques can be incorporated with a minimal performance degradation and area overhead, and are independent of the multiplier architecture. Experimental analysis performed on four high-revel synthesis benchmarks exhibits a significant improvement in the overall testability of the corresponding data-path implementations.