Neural network (NN) operation has high requirements for storage resources and parallel computing, which bring huge challenges to the deployment of NNs in Internet-of-Things (IoT) devices. Consequently, this work proposed a low-power NN architecture, comprising an energy-efficient NN processor and a Cortex-M3 host processor to achieve state-of-the-art (SOTA) end-to-end inference at the edge. The innovations of this article are as follows: 1) to minimize the bit width of the weight while keeping the loss of accuracy within a small range, cross-layer error tolerance has been analyzed, and mixed precision quantization has been adopted for cross-layer mapping; 2) dynamic reconfigurable tensor processing unit (DR-TPU) with approximate computing has been proposed, which brings$1.45\times $computing energy reduction within 0.46% accurate loss in ResNet-50; and 3) a customized input feature map (IFM) reuse and over-writeback strategy has been adopted, eliminating the recurrent fetching from the on-chip and off-chip memories. The times of on-chip storage access can be reduced by 25%–60%, and the capacity of on-chip memory can be reduced to half of the original. The processor has been implemented at 28-nm CMOS technology. Combining the above work, the proposed architecture can achieve a 53.1% reduction of power and 17.2-TOPS/W energy efficiency.

As the artificial intelligence and Internet of Things (AIoT) develop rapidly, the deployment of artificial neural networks in edge computing is becoming significant with great challenge. The binarized convolutional neural network (BCNN) is one of the most widely adopted light-weight ANNs in AIoT, which can achieve the balance of system accuracy and hardware resource consumption, compared to others. To achieve high power and area efficiency in BCNN deployment, many approximate computing (AxC) techniques are integrated to make full use of the resilience of BCNN. As the research focused on the integration of AxC in circuit design, the design of AxC itself is not fully considered when applied to specific applications or domains. Based on circuit-architecture-system co-design, this article proposes an efficient BCNN deployment method, including a quality-circuit co-design method for approximate adder generation, a quality-aware intercompensation approach for addition tree, and a computing quality involved retraining approach for BCNN deployment. Experimental results show that the proposed quality model can achieve 86.43% in average accuracy while evaluating nine types of typical approximate adders. The proposed method is conducted on the applications of keyword spotting of GSCD, MNIST, and CIFAR-10, and we can further rise the approximation degree by 50%–75%, while reducing the accuracy by less than 1%.