上海科技大学知识管理系统

Transient bit flips may cause unexpected behaviors in digital arithmetic circuits, and thus computation errors. It is generally believed that stochastic computing (SC) can tolerate bit flips due to its unique number representation format. In SC, a value is encoded by a random bit stream using the probability of 1s in the bit stream. Therefore, one bit flip changes the probability by a small number given a long enough bit stream, and the computation results might not change much. This is verified in previous works mostly through empirical studies. However, we found that bit flips actually change the probability of a stochastic bit stream by a predictable value. This is formulated by considering the bit flips as Bernoulli events. The distorted probability of the bit stream considering bit flips is derived and the SC bit flip models for various stochastic circuits are proposed. The error recovery based on the formulation is also proposed. The SC bit flip model and error recovery scheme are verified on basic SC elements such as the SC multipliers and an FSM-based stochastic circuit. They are then applied to a complex SC system computing a neural network. The results show that the accuracy of MNIST digit recognition can be recovered even with a high bit flip rate of 10%. © 2024 Owner/Author.