AL-MAC: Adaptive Error Compensation Approximate MAC

Approximate calculation is extensively used in fault-tolerant applications as an extremely effective method of saving energy by balancing performance between accuracy and power consumption. Herein, an adaptive error compensation approximate multiplication and accumulation (AL-MAC) based on the logarithmic principle is proposed, which takes two factors into account. (a) LFC (leftmost-one filtering circuit) extracts the valid bits of the input data for calculation, thus reducing the circuit power consumption and area caused by unnecessary level flipping; (b) ACC (adaptive compensation circuit) conducts the adaptive error compensation, which is compensated according to the error distribution regulation. The evaluation results show that the proposed AL-MAC can save 33.8% of the power consumption and 19.38% of the area in a processing element of the neural network hardware accelerator compared with the standard exact MAC. Moreover, it has good performance on image processing.