Fully analog compute-in-memory architecture for neural networks

Abstract

A Fully Analog STate-Space Compute-In-Memory (FAST-CIM) architecture implements cascaded CIM arrays that maintain continuous analog signal flow throughout neural network computations. Sequential data patches are processed through cascaded CIM arrays, where a feedforward CIM array performs initial vector-matrix multiplication using analog computations within memory cells, and the analog output flows directly through a gain circuit to a recurrent CIM array without digital conversion. The gain circuit converts analog current signals to voltage signals, enabling direct analog connection between the cascaded arrays. The recurrent CIM array executes State-Space Model (SSM) computations, processing the cascaded analog signals along with previous state information maintained by a State Write and Propagate (SWAP) circuit that stores states using capacitive elements. The cascaded array configuration eliminates analog-to-digital and digital-to-analog converters between processing stages, achieving reduced power consumption and latency compared to conventional implementations that require digital interfaces between CIM arrays.