Dynamic Approximation with Feedback Control for Energy-Efficient Recurrent Neural Network Hardware

This paper presents methodology of feedback-controlled dynamic approximation to enable energy-accuracy trade-off in digital recurrent neural network (RNN). A low-power digital RNN engine is presented that employs the proposed dynamic approximation. The on-chip feedback controller is realized by utilizing hysteretic or proportional controller. The dynamic adaptation of bit-precisions during the RNN computation is selected as approximation approach. Considering various applications, the digital RNN engine designed in 28nm CMOS shows ~36% average energy saving compared to the baseline case, with only ~4% of accuracy degradation on average.