b-HiVE: A bit-level history-based error model with value correlation for voltage-scaled integer and floating point units

Existing timing error models for voltage-scaled functional units ignore the effect of history and correlation among outputs, and the variation in the error behavior at different bit locations. We propose b-HiVE, a model for voltage-scaling-induced timing errors that incorporates these attributes and demonstrates their impact on the overall model accuracy. On average across several operations, b-HiVE´s estimation is within 1-3% of comprehensive analog simulations, which corresponds to 5-17x higher accuracy (6-10x on average) than error models currently used in approximate computing research. To the best of our knowledge, we present the first bit-level error models of arithmetic units, and the first error models for voltage scaling of bitwise logic operations and floating-point units.