Ageing Simulation of Analogue Circuits and Systems using Adaptive Transient Evaluation
Felix Salfeldera and Lars Hedrichb
Electronic Design Methodology, Department of Computer Science, Goethe-Universität Frankfurt a.M.
Simulating ageing effects in analogue circuits requires both ageing models and a circuit simulator which is capable of a stress dependent, ageing and recovery aware model evaluation during long term transient simulation. Common approaches on reliability simulation often involve aged models, age precomputation, or lookup tables instead of integrated ageing simulation using memory aware ageing models. Long term transient ageing simulation enhances reliability simulation. This paper presents a framework to model and simulate ageing effects using an adaptive two-times evaluation scheme. This integrates full ageing effect models into behavioural device models. In addition, we introduce semantics for modelling stress levels and ageing parameters in hardware description languages. Our approach is a fully integrated simulation solution, enabling correct and efficient simulation of ageing systems over their lifetimes. We demonstrate how transistor level ageing effects critically affect the operation of a circuit. Our examples incorporate ageing monitors, redundant parts, and self-repair functionality into analogue systems.
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