SUTD researchers develop a novel reconfigurable device that can bridge the gap between processor and memory

31 Jan 2023 Science, Mathematics and Technology Computer Science, Mechanical Engineering

SUTD - Shao-Xiang Go, Qiang Wang, Natasa Bajalovic and Desmond Loke
University of Cambridge - Tae Hoon Lee
Zhejiang University - Kejie Huang

Schematic representation of the data loading to and retrieval from the device that occurs in the serial model and parallel mode, respectively (left panel) and the table showing changes of the states in the three bits during operations (right panel).

Developing energy efficient high performing computing devices, i.e., devices that not only consume little power, but also compute information rapidly, is a key goal of edge computing research. Combining the memory components and units that perform shift register operations is a potential way to achieve this goal.

Most computing devices are made up of a physically separate memory component and processing unit. However, to substantially simplify these devices and reduce its power consumption, a device that can potentially perform both functions efficiently – the shift register-in-memory architecture – has been developed.

Conventional shift register-in-memory architectures have limitations, although some of these architectures show promising results. The limitations include the use of many devices and the requirement to convert the electrical resistance to electric signals.

Based on phase-change alloys, materials that switch reversibly between the glassy amorphous state and the ordered crystal state, researchers at the Singapore University of Technology and Design (SUTD) have developed a new reconfigurable shift register-in-memory architecture. Their device works both as a reconfigurable memory component and as a programmable shift register and has been introduced in a paper published in Advanced Intelligent Systems.

The term “material (M) state-based shift register” was used to describe the shift register-in-memory device developed by the researchers. The four material states, i.e., the amorphous state, fully crystalline state, partially crystallised state and primed state, of the phase-change material (representing different shift register/ memory modes) were used to operate the device.

The device can be switched to perform either shift register or memory functions and is easily programmable due to its special design. The researchers showed that the device performed impressively for both functions in preliminary tests.

“When operating as a memory, the device can be switched from the disordered glass state to crystalline state with 1.9 ns pulses, which is about one-third shorter than those of existing devices with germanium antimony telluride layers doped with nitrogen; and exhibit a resetting energy of 2 pJ. When operating as a shift register, the device can be switched between the serial-in–serial-out mode to serial-in–parallel-out mode, with a single cell, and exhibit many resistance levels, which has not been shown before,” said SUTD’s Assistant Professor Desmond Loke, who is the principal investigator of the study.  

To substantially reduce the power consumption, the new shift register-in-memory architecture proposed by the research team could be used to design a wide range of high-performance electronic systems in the future. The M state-based shift registers could be applied to a variety of operation schemes and computations, although for the purpose of this research, the researchers have shown that these devices are able to perform shift register operations successfully.

Other researchers involved in this work were Shao-Xiang Go, Qiang Wang, Natasa Bajalovic from SUTD, Taehoon Lee from University of Cambridge and Kejie Huang from Zhejiang University.

The authors thank S.R. Elliott (University of Cambridge), A.M. Belcher (Massachusetts Institute of Technology), and T.C. Chong (Singapore University of Technology and Design) for support, and K.G. Lim and L.T. Ng for important discussions. The authors acknowledge support from the SUTD (SUTDT12017003), Changi General Hospital (Singapore) (CGH-SUTD-HTIF2019-001), SUTD Kickstarter Initiative (SKI 2021_02_03, SKI 2021_01_04, SKI 2021_02_17), Ministry of Education (Singapore) (MOE-T2EP50220-0022), SUTD-Zhejiang-University (SUTD-ZJU (VP) 201903), and Agency of Science, Technology and Research (Singapore) (A20G9b0135) grant programs. D.K.L. acknowledges support from the Massachusetts Institute of Technology—SUTD International Design Centre and National Supercomputing Centre, Singapore (15001618). S.X.G acknowledges support from the SUTD President Graduate Scholarship.

Toward Single-Cell Multiple-Strategy Processing Shift Register Powered by Phase-Change Memory Materials, Advanced Intelligent Systems. (DOI: 10.1002/aisy.202200353)