ArPCIM: An Arbitrary-Precision Analog Computing-in-Memory Accelerator With Unified INT/FP Arithmetic

Analog Computing-in-memory (ACIM) breaks the von Neumann bottleneck and significantly improves energy efficiency by enabling parallel matrix-vector-multiplication (MVM) operations. However, most existing ACIM accelerators are highly customized for specific precision formats, lacking the generality to support efficiently arbitrary precision in both integer (INT) and floating-point (FP) formats. In this work, we present an arbitrary precision analog computing-in-memory (ArPCIM) accelerator with unified INT/FP arithmetic to address this limitation. We introduce a CIM-friendly INT/FP arithmetic to convert FP numbers into INT numbers for efficient execution on CIM, minimizing precision loss through local pre-alignment and dynamic bit-weight slicing methods. In addition, we implement multi-level reconfigurable precision circuits, featuring both intra- and inter-processing element (PE) reconfigurability, which supports precision ranging from 1-bit to 47-bit. Experimental results show that our ArPCIM accelerator achieves up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.09\times $ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.37\times $ </tex-math></inline-formula> improvement in energy efficiency and area efficiency, respectively, compared with state-of-the-art arbitrary precision digital CIM. Our ArPCIM accelerator offers the flexibility to meet diverse computational needs while maintaining high energy efficiency and accuracy, paving the way for versatile CIM acceleration across various fields.