DBP-CIM: Energy-Efficient 8T SRAM-Based Diagonal-Block Parallel Computing-in-Memory With Compact Data Layout for Arithmetic Operations

In this work, an energy-efficient bit-parallel static random-access memory (SRAM)-based computing-in-memory (SRAM-CIM) is proposed for general-purpose in-memory arithmetic operations to adapt diverse computing tasks. A compact diagonal-block parallel (DBP) mapping scheme and a novel arithmetic flow are proposed to address the hardware underutilization issue in conventional two-sided stationary bit-parallel CIM architectures. Specifically, the DBP mapping method is implemented to enhance the throughput by reorganizing the intermediate and final results into diagonal memory blocks, effectively reducing the vacant CIM cells caused by the dynamic bit width during computing. In addition, the proposed hardware-efficient arithmetic flows employ: 1) a pipelined ADD scheme to reduce the critical path latency in near-memory computing units; and 2) shift-based arithmetic operations that halve the hardware resources required for multiplication and division while reducing energy consumption. The post-layout simulations on 28-nm CMOS technology show that the proposed DBP-CIM achieves higher energy efficiency and throughput for general-purpose arithmetic operations, compared with state-of-the-art works. Furthermore, evaluations on the general-purpose benchmarks demonstrate that the DBP-CIM reduces energy consumption and computing cycles by up to 55.9% and 60.9%, compared to the conventional bit-parallel CIM.