Title
15.2 A 28nm 64kb Inference-Training Two-Way Transpose Multibit 6t Sram Compute-In-Memory Macro For Ai Edge Chips
Abstract
Many Al edge devices require local intelligence to achieve fast computing time (t AC ), high energy efficiency (EF), and privacy. The transfer-learning approach is a popular solution for Al edge chips, wherein data used to re-train the Al in the cloud is used to fine-tune (re-train) a few of the neural layers in edge devices. This enables the dynamic incorporation of data from in-situ environments or private information. Computing-in-memory (CIM) is a promising approach to improve EF for Al edge chips, existing CIM schemes support inference [1]–[5] with forward (FWD) propagation; however, they do not support training, requiring both FWD and backward (BWD) propagation, due to differences in weight-access flow for FWD and BWD propagation. As Fig. 15.2.1 shows, efforts to increase the precision of the input (IN), weight (W), and/or output (OUT) tend to degrade r AC and EF for training operations irrespective of scheme: digital FWD and BWD (DF-DB) or CIM-FWD-digital-BWD (CiMF-DB). This work develops a two-way transpose (TWT) SRAM-CIM macro supporting multibit MAC operations for FWD and BWD propagation with fast r AC and high EF within a compact area. The proposed scheme features (1) A TWT multiply cell (TWT-MC) with a high resistance to process variation; and (2) a small-offset gain-enhancement sense amplifier (SOGE-SA) to tolerate a small read margin. A 28nm 64Kb TWT SRAM-CIM macro was fabricated using a foundry-provided compact 6T-SRAM cell for SRAM-CIM devices supporting both inference and training operations for the first time. This macro also demonstrates the fastest t AC (3.8 – 21ns) and highest EF (7 – 61.1TOPS/w) for MAC operations using 2 – 8b inputs, 4 – 8b weights and 12 − 20b outputs.
Year
DOI
Venue
2020
10.1109/ISSCC19947.2020.9062949
2020 IEEE INTERNATIONAL SOLID- STATE CIRCUITS CONFERENCE (ISSCC)
DocType
ISSN
Citations 
Conference
0193-6530
0
PageRank 
References 
Authors
0.34
0
23
Name
Order
Citations
PageRank
Jian-Wei Su1133.61
Xin Si2496.86
Yen-Chi Chou382.20
Ting-Wei Chang4245.30
Wei-Hsing Huang5252.56
Yung-Ning Tu6262.92
Ruhui Liu720.73
Pei-Jung Lu871.81
Ta-Wei Liu972.83
Jing-Hong Wang10314.03
Zhixiao Zhang1182.87
Hongwu Jiang12166.77
Shanshi Huang13156.75
Chung-Chuan Lo14157.24
Ren-Shuo Liu151419.86
Chih-Cheng Hsieh1621844.84
Kea-Tiong Tang1710928.91
Shyh-Shyuan Sheu1821123.45
Sih-Han Li1971.80
Heng-Yuan Lee2022820.66
Shih-Chieh Chang2164152.31
Shimeng Yu2249056.22
Meng-Fan Chang2345945.63