Evaluation Platform of Time-Domain Computing-in-Memory Circuits

Computing-in-memory (CIM) architecture is considered an effective way to reduce the energy efficiency of deep neural networks (DNNs). Compared with conventional all digital implementations, time-domain CIM designs have shown great potential with better energy efficiency and less area cost. However, due to the non-idealities of devices and PVT variations, time-domain CIM may face computational errors, resulting in the reduction of network accuracy. In this brief, we proposed an evaluation platform based on typical time-domain CIM circuits to optimize the design process. Non-idealities in CIM calculation and the impact of key parameters on the network accuracy were analyzed. Based on this evaluation platform, a 28nm time-domain CIM test chip with configurable computing channels was fabricated. Under 2–128 computing channels, the measurement results show the same trend as proposed evaluation platform. And this chip achieved 66.8 TOPS/W energy efficiency and 80.68% inference accuracy based on the CIFAR-10 dataset.