TY - JOUR
T1 - A 28-nm Digital Transpose SRAM Compute-in-Memory Macro With Accurate/Approximate Dual Mode for Floating-Point Edge Training and Inference
AU - Yuan, Yiyang
AU - Zhang, Bingxin
AU - Yang, Yiming
AU - Luo, Yishan
AU - Chen, Qirui
AU - Wang, Haitao
AU - Liu, Qihao
AU - Chen, Zhiming
AU - Wu, Hao
AU - Yue, Jinshan
AU - Lv, Shidong
AU - Wang, Xinghua
AU - Mak, Pui In
AU - Li, Xiaoran
AU - Zhang, Feng
N1 - Publisher Copyright:
© 1966-2012 IEEE.
PY - 2026
Y1 - 2026
N2 - Static random-access memory (SRAM)-based computing-in-memory (CIM) macros have been widely studied to improve the energy efficiency of edge artificial intelligence (AI) inference tasks. However, less attention has been given to AI training, which requires CIM macros to not only perform matrix multiply-accumulate (MAC) operations but also support matrix transposition. To address the limitations of previous analog transpose and digital non-transpose SRAM CIM macros, this work features: 1) a cyclic-weight-mapping SRAM array that enables matrix transposition and reuse of MAC circuits during both feed-forward (FF) and back-propagation (BP) phases; 2) a digital CIM architecture employing signed fixed-point mantissa encode and a vector-wise pre-alignment (VWPA) scheme, supporting multiple data formats including INT4/8, FP8, and BF16; and 3) an accurate/approximate dual-mode bit-parallel MAC circuit (DMBP-MAC) designed to provide a tradeoff between computational accuracy and energy efficiency. A fabricated 28-nm 32-kB transpose SRAM CIM macro achieved average energy efficiency of 70.2–285.4 TOPS/W in INT4, 17.5–71.4 TOPS/W in INT8, 51.1–192.3 TFLOPS/W in FP8, and 12.8–48 TFLOPS/W in BF16.
AB - Static random-access memory (SRAM)-based computing-in-memory (CIM) macros have been widely studied to improve the energy efficiency of edge artificial intelligence (AI) inference tasks. However, less attention has been given to AI training, which requires CIM macros to not only perform matrix multiply-accumulate (MAC) operations but also support matrix transposition. To address the limitations of previous analog transpose and digital non-transpose SRAM CIM macros, this work features: 1) a cyclic-weight-mapping SRAM array that enables matrix transposition and reuse of MAC circuits during both feed-forward (FF) and back-propagation (BP) phases; 2) a digital CIM architecture employing signed fixed-point mantissa encode and a vector-wise pre-alignment (VWPA) scheme, supporting multiple data formats including INT4/8, FP8, and BF16; and 3) an accurate/approximate dual-mode bit-parallel MAC circuit (DMBP-MAC) designed to provide a tradeoff between computational accuracy and energy efficiency. A fabricated 28-nm 32-kB transpose SRAM CIM macro achieved average energy efficiency of 70.2–285.4 TOPS/W in INT4, 17.5–71.4 TOPS/W in INT8, 51.1–192.3 TFLOPS/W in FP8, and 12.8–48 TFLOPS/W in BF16.
KW - Approximate computing
KW - artificial intelligence (AI)
KW - computing-in-memory (CIM)
KW - floating point (FP)
KW - static random-access memory (SRAM)
UR - https://www.scopus.com/pages/publications/105036246759
U2 - 10.1109/JSSC.2026.3679560
DO - 10.1109/JSSC.2026.3679560
M3 - Article
AN - SCOPUS:105036246759
SN - 0018-9200
JO - IEEE Journal of Solid-State Circuits
JF - IEEE Journal of Solid-State Circuits
ER -