An Area and Energy-Efficient Systolic Array Accelerator Architecture for Deep Neural Networks Using Stochastic Computing

Deep neural networks (DNNs) are widely used to handle various intelligent tasks. With the increased model size, the DNNs’ hardware accelerators are challenging the higher area overhead and energy consumption. Stochastic computing (SC) has recently been considered for implementing DNNs and reducing hardware consumption. However, many current SC-based DNN accelerators fail to balance accuracy, performance, and resource overhead. In addition, their limited scalability and flexibility restrict their use in edge devices. In this article, we design an area and energy-efficient DNN accelerator architecture using SC. We propose an SC-binary hybrid processing unit with piecewise shift compensation without significant additional hardware overhead increment to improve the SC accuracy. To balance performance and resource overhead, we conduct a design space exploration (DSE) from an overall architectural perspective. An experimental platform with both software and hardware for SC-based DNNs is established. The software simulation results demonstrate that the best accuracy of the designed SC-DNN on the CIFAR-10 is 91.9%, which is 3.2% higher than that of the previous SC-DNN work. The VLSI implementation of the hardware is synthesized using the TSMC 28-nm CMOS process. Results show that compared to the binary computing counterpart, our design achieves <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.7\times $ </tex-math></inline-formula> area efficiency and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.4\times $ </tex-math></inline-formula> energy efficiency. Compared to other SC-DNN accelerator designs, our design can provide <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.3\times $ </tex-math></inline-formula> area efficiency and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.3\times $ </tex-math></inline-formula> energy efficiency.