An Energy-Efficient Mixed-Bit ReRAM-based Computing-in-Memory CNN Accelerator with Fully Parallel Readout

Computing-In-memory (CIM) accelerators have the characteristics of storage and computing integration, which has the potential to break through the limit of Moore's law and the bottleneck of Von-Neumann architecture. However, the performance of CIM accelerators is still limited by conventional CNN architectures and inefficient readouts. To increase energy-efficient performance, optimized CNN model is required and low-power fully parallel readout is necessary for edge-computing hardware. In this work, an ReRAM-based CNN accelerator is designed. Mixed-bit 1~8-bit operations are supported by bitwidth configuration scheme for implementing Neural Architecture Search (NAS)-optimized multi-bit CNNs. Besides, energy-efficient fully parallel readout is achieved by variation-reduction accumulation mechanism and low-power readout circuits. Benchmarks show that the proposed ReRAM accelerator can achieve peak energy efficiency of 2490.32 TOPS/W for 1-bit operation and average energy efficiency of 479.37 TOPS/W for 1~8-bit operations when evaluating NAS-optimized multi-bitwidth CNNs.