A 5.1pJ/Neuron 127.3us/Inference RNN-based Speech Recognition Processor using 16 Computing-in-Memory SRAM Macros in 65nm CMOS

This work presents a 65nm CMOS speech recognition processor, named Thinker-IM, which employs 16 computing-in-memory (SRAM-CIM) macros for binarized recurrent neural network (RNN) computation. Its major contributions are: 1) A novel digital-CIM mixed architecture that runs an output-weight dual stationary (OWDS) dataflow, reducing 85.7% memory accessing; 2) Multi-bit XNOR SRAM-CIM macros and corresponding CIM-aware weight adaptation that reduces 9.9% energy consumption in average; 3) Predictive early batch-normalization (BN) and binarization units (PBUs) that reduce at most 28.3% computations in RNN. Measured results show the processing speed of 127.3us/Inference and over 90.2% accuracy, while achieving neural energy efficiency of 5.1pJ/Neuron, which is 2.8 × better than state-of-the-art.