Methodology for low power test pattern generation using activity threshold control logic

This paper proposes a new technique of power-aware test pattern generation, wherein the test mode power constraints are specified using pseudo hardware logic functions (referred to as power constraint circuits) that augment the target circuit fed to the ATPG tool. The novelty of this approach is three-fold: (i) The ATPG tool only sees the enhanced circuit. This influences the generation of the test cubes themselves, as against post-processing of these cubes for a given pattern. (ii) Pattern generation can be driven to minimize test power according to a programmable switching activity threshold, and hence, is scalable. (iii) The same constraint circuit can also be effectively used for pattern filtering to isolate patterns which cause high switching activity. Additionally, the proposed method does not require any changes to the pattern generation tool or process. This paper describes the methodology, together with techniques for realizing the hardware circuit and specifying thresholds. Experimental results on various benchmark circuits (including an industrial design) are presented to show the effectiveness of this approach.