Test-Friendly Data-Selectable Self-Gating (DSSG)

Abstract

Low-power design is a key consideration in modern design. XOR self-gating (data-driven self-gating) is used for power reduction in clock networks, which is one of the main factors of dynamic power consumption. When applying XOR self-gating, dynamic power consumption is reduced, but the number of required test patterns on the testing side is inflated. In critical cases, more than three times the regular number of scan test patterns may be required for industrial designs, such as GPUs. In this brief, we propose a novel self-gating structure. Data-selectable self-gating (DSSG) is designed to use functional data and scan data selectively to eliminate the unnecessary clock toggling of flip-flops. With this structure, the self-gating function can be used in the scan test mode, as well as the function mode. When the self-gating logic is used during scan shift operations, the stuck-at faults in the self-gating logic can be tested with short test sequences; therefore, the rise in test costs can be mitigated. It is possible to test the stuck-at faults in self-gating logic using only four scan test patterns. The experimental results show that the average of the stuck-at test pattern increase ratio has been dropped from more than 90% to less than 8%. The low-power performance of the proposed method in the mission mode is the same as that of the conventional self-gating structures. When the DSSG method is used, the dynamic power of the shift operation which may increase excessively during the scan test can be reduced.