A T8T-SRAM Computing-in-Memory Macro for Ternary Deep Neural Networks and Boolean Logic Computations

Deep neural networks (DNNs) play important roles in artificial intelligence applications and show hungry computility and power demands. Compared with binary neural networks (BNNs), ternary neural networks (TNNs) have higher representation and adaptive abilities and balance the inference accuracy and computing efficiency between DNNs and BNNs. This article proposed a T8T-SRAM computing-in-memory (CIM) macro to achieve Boolean logic operations and MAC operation of ternary activation and ternary weight. The proposed T8T-SRAM bitcell has a separate read and write path, and can avoid the read disturb issue. In Boolean logic operation mode, the T8T-SRAM macro can achievenand,nor,xnor, andxoroperations with redundant rows, reducing the additional reference voltage generation circuit. In the MAC mode, the result is quantized by an embedded column analog-to-digital converter (ADC), which uses activation refresh to reduce weight changing. In 28-nm CMOS technology, under 0.5-V array supply voltage and 0.9-V peripheral supply voltage, simulation results manifest that the MAC results have good linearity, and feasibility of Boolean logic operation. The proposed T8T-SRAM macro realizes MAC operation of 16 ternary activations and 16 ternary weights with 333.99–816.1-TOPS/W energy efficiency and 61.9-TOPS/mm2area efficiency. Using an ResNet-18 network for the inference of MNIST, and CIFAR-10 datasets, the accuracies were 99.06% and 85.76% with a ternary activation and ternary weight.