Path selection and sensor insertion flow for age monitoring in FPGAs

This paper presents a two-step aging-aware methodology for Representative Critical Paths (RCPs) selection from a large number of Critical Paths (CPs) in programmable logic devices. First, nomination of CPs is based on delay, temperature, and lexicographic function of duty cycle and switching activity filtering, which are the major causes in Bias Temperature Instability (BTI) and Hot Carrier Injection (HCI) aging mechanisms. Secondly, RCPs will be selected based on Fan-out (FO) and physical location of Logic Blocks (LBs) along a CP to decrease aging propagation and sensor distribution fairness, respectively. We then present a sensor insertion algorithm that will be used during design placement to avoid sensors inaccuracy. Implementation steps of sensor insertion are performed automatically with a limited human interaction. Higher aging-rate of RCPs than unselected CPs in our experiments demonstrates the effectiveness of the proposed methodology.