Aging in digital circuits and age monitoring: Object-oriented modeling and evaluation

Transistor and interconnect wearout is accelerated with transistor scaling resulting in timing variations and consequently reliability challenges in digital circuits. Age monitoring methods can be used to predict and deal with the aging problem. Selecting appropriate locations for placement of hardware aging monitors is an important issue. In this work we propose a procedure for selection of appropriate internal nodes in combinational clouds between pipeline stages or combinational parts of a sequential circuit to place hardware monitors that can effectively provide aging information of various components of a modern digital system. In order to implement the node selection procedure, we propose an object-oriented model. Object-oriented model of a circuit along with a probabilistic and logical simulation engine that we have developed can effectively be used for implementation and also fast evaluation of the proposed node selection mechanism. The proposed object-oriented C+ + models can be integrated into a SystemC RTL model making it possible to perform mixed-level simulation, and integrated evaluation of a complete system. We have applied our proposed scheme to several processors including MIPS, ARM, ALPHA and MiniRISC and have looked at its effectiveness for these processors.