Soft Delay Error Analysis in Logic Circuits

In this paper, we present an analysis methodology to compute circuit node sensitivity due to charged particle induced delay (timing) errors, soft delay errors (SDE). We define node sensitivity metric and describe a step by step procedure to compute node sensitivity. We use mixed-mode simulations to extract accurate current pulses for the characterization of SDE. A technique for logic cell library characterization for SDE is described. Our approach is orders of magnitude faster than using Spice based analysis and its accuracy is close to Spice. Using our approach, we provide distribution of nodes sensitivity for various ISCAS85 circuits and two adders. Such analysis is important to employ node hardening techniques on selected nodes to increase the reliability of CMOS circuits. We use two test circuits to apply a node hardening technique on the highly sensitive nodes which were determined by our approach. Results are provided for the reduction of the circuit sensitivity