Abstract
This article proposes a 256 × 128 in-memory computing array using reconfigurable in-memory analog-to-digital conversion with shared references for high area efficiency (area overhead of 3% is 9X better than traditional). A dual-8T SRAM bitcell is used to achieve read-write decoupling and store ternary weights. Read World Line Under Drive enabled Cascode helps to minimize current variations producing high linearity. Multi-bit input is handled with low latency and high energy-efficiency by using bit-slicing (BS) with near-memory charge-sharing based binary weighted accumulator (CHA). Using noise resilient training, we show software comparable performance for a MLP on MNIST, VGG-8 on CIFAR-10, and graph attention network on Cora, with respective accuracy reductions of only 0.1%, 0.8% and 0.5% due to non-idealities. The proposed macro demonstrates high energy/area efficiency (1146 TOPS/W, 27 TOPS/mm2 at 1/2/1b) in 65nm CMOS. It increases throughput (by 1.9X) and linearity (by 23X) compared to input pulse-width modulation by using BS and CHA. Compared to conventional BS with digital accumulation after ADC, this method has 1.7X/6.6X better energy-efficiency/throughput by reducing ADC operations. © 2025 IEEE.
| Original language | English |
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| Title of host publication | 2025 62nd ACM/IEEE Design Automation Conference (DAC) |
| Publisher | IEEE |
| Number of pages | 7 |
| ISBN (Electronic) | 979-8-3315-0304-8 |
| DOIs | |
| Publication status | Published - 2025 |
| Event | 62nd ACM/IEEE Design Automation Conference, DAC 2025 - San Francisco, United States Duration: 22 Jun 2025 → 25 Jun 2025 |
Publication series
| Name | Proceedings - Design Automation Conference |
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| ISSN (Print) | 0738-100X |
Conference
| Conference | 62nd ACM/IEEE Design Automation Conference, DAC 2025 |
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| Place | United States |
| City | San Francisco |
| Period | 22/06/25 → 25/06/25 |
Funding
This work was supported by the Innovation Technology Fund Mid-Stream Research Program (ITF MSRP) under Grant ITS/018/22MS. Any opinions, findings, conclusions, or recommendations expressed in this material do not reflect the views of the Government of the Hong Kong Special Administrative Region, the Innovation and Technology Commission, or the Innovation and Technology Fund Research Projects Assessment Panel. (Junyi Yang and Shuai Dong contributed equally to this work.)
Research Keywords
- Charge-sharing
- In-memory ADC
- In-memory computing
- Multi-bit
- SRAM