MAC-DO: Multi-bit analog in-memory accelerator compatible with DRAM using output stationary

Abstract

This paper presents an analog accelerator in-memory (AiM) architecture named MAC-DO which is compatible with modern DRAM technology. Compared to previous analog accelerators, MAC-DO has four key benefits. First, MAC-DO supports multi-bit input and weight precision for multiply-accumulate (MAC) operations. Secondly, MAC-DO is compatible with current 1T1C DRAM technology without any modifications of a DRAM cell and array. Third, MAC-DO makes all DRAM cells participate in MAC computations without idle cells during a MAC operation cycle by using output stationary mapping, which leads to the improvement of throughput and energy efficiency. Fourth, MAC-DO uses charge stored in capacitors to compute MAC operations instead of current, and it improves the linearity of MAC operations.