With the down-scaling of CMOS technology, the design complexity of very large-scale integrated is increasing. Although the application of machine learning (ML) techniques in electronic design ...automation (EDA) can trace its history back to the 1990s, the recent breakthrough of ML and the increasing complexity of EDA tasks have aroused more interest in incorporating ML to solve EDA tasks. In this article, we present a comprehensive review of existing ML for EDA studies, organized following the EDA hierarchy.
Under the von Neumann computing architecture, the edge devices used for artificial intelligence (AI) and the Internet of Things (IoTs) are limited in terms of latency and energy efficiency due to the ...movement of data between the memory and the processor. Nonvolatile memory-based computation-in-memory (nvCIM) is a promising candidate to overcome this issue, referred to as the memory wall. This article outlines the background and major challenges in the development of nvCIM macros as well as some of the recent progress in nvCIM for logic computation, pattern-matching computation, and multiply-and-accumulate (MAC) computation. We also summarize recent trends in nvCIM development at the end of each section.
Compute-in-memory (CiM) is a promising approach to alleviating the memory wall problem for domain-specific applications. Compared to current-domain CiM solutions, charge-domain CiM shows the ...opportunity for higher energy efficiency and resistance to device variations. However, the area occupation and standby leakage power of existing SRAM-based charge-domain CiM (CD-CiM) are high. This brief proposes the first concept and analysis of CD-CiM using nonvolatile memory (NVM) devices. The design implementation and performance evaluation are based on a proposed 2-transistor-1-capacitor (2T1C) CiM macro using ferroelectric field-effect-transistors (FeFETs), which is free from leakage power and much denser than the SRAM solution. With the supply voltage between 0.45V and 0.90V, operating frequency between 100MHz to 1.0GHz, binary neural network application simulations show over 47%, 60%, and 64% energy consumption reduction from existing SRAM-based CD-CiM, SRAM-based current-domain CiM, and RRAM-based current-domain CiM, respectively. For classifications in MNIST and CIFAR-10 data sets, the proposed FeFET-based CD-CiM achieves an accuracy over 95% and 80%, respectively.
Bitwise logic-in-memory (BLiM) is a promising approach to efficient computing in data-intensive applications by reducing data movement between memory and processing units. However, existing BLiM ...techniques have challenges towards higher energy efficiency and speed: (i) DC power in computing and result sensing is significant in most existing RRAM and MRAM based BLiM solutions; (ii) before the computation result could be stored back to the same memory array, existing BLiM has to sense the result first, at the cost of extra power and latency due to the sense amplifiers (SAs). Targeting at higher energy efficiency and speed, this work proposes a new BLiM approach in 2-transistor/ cell (2T/C) and 3T/C topologies based on ferroelectric field-effect transistors (FeFETs), supporting a variety of computing functions. For the first time, this new approach supports SA-free direct write-back, and consumes no static power for computing and sensing with proposed fully dynamic computing and sensing schemes. Another highlight is that this work further minimizes the dynamic power by (i) reducing the chance of bitline charging activities and (ii) recycling the bitline charge in sensing multi-operand operations. Compared with prior BLiM methods based on nonvolatile memories, evaluation shows 3.0x-100x latency and 1.3x-200x energy improvement for typical in-memory xor operation, which further leads to 3.0x-58x and 3.2x-78x savings of latency and energy, respectively, for the application of advanced-encryption standard (AES).
This paper proposes C 2 FeRAM, a 2T2C/cell ferroelectric compute-in-memory (CiM) scheme for energy-efficient and high-reliability edge inference and transfer learning. With certain area overhead, C 2 ...FeRAM achieves the following highlights: (i) compared with FeFET/FeMFET, it achieves disturb-free CiM and much higher write endurance (equal to FeRAM), leading to >100x inference time with <1% accuracy drop for VGG8 in CIFAR-10 dataset, along with the enhanced endurance for weight updates, e.g., CiM-based transfer learning; (ii) compared with 1T1C FeRAM inference cache, the achieved disturb-free feature and CiM capability in C 2 FeRAM lead to improvements of 4x energy, 200x speed, and 3.2e5x life cycles. Such benefits highlight an intriguing solution for future intelligent edge AI.
Hyperdimensional computing (HDC) is an emerging paradigm that employs hypervectors (HV s) to emulate cognitive tasks. In HDC, the most time-consuming and power-hungry process is encoding, the first ...step that maps raw data into HV s. There have been non-volatile memory (NVM) based computing-in-memory (CiM) HDC encoding designs, which exploit the intrinsic HDC characteristics of high parallelism, massive data, and robustness. These NVM-based CiMs have shown great potential in reducing encoding time and power consumption. Among them, the ferroelectric field-effect transistor (FeFET) based designs show ultra-high energy efficiency. However, existing FeFET-based HDC encoding designs face the challenges of energy -consuming current-mode addition, inefficient HV storage, limited endurance, and single encoding method support. These challenges limit the energy efficiency, lifetime, and versatility of the designs. This work proposes an energy-efficient charge-domain FeFET-based in-memory HDC encoder, i.e., CafeHD, with extended lifetime, good versatility, and comparable accuracy. Area-efficient charge-domain computing is proposed in HDC encoding for the first time, which enables CafeHD with ultra-low power and high scalability. An HV merging technique is explored to improve the performance. A low-cost partial MAJ interface is also proposed to reduce writes. Besides, CafeHD also supports two widely used encoding methods. Results show that CafeHD on average achieves 10.9×/12.7×/3.5× speedup and 103.3×/21.9×/6.3× energy effi-ciency with ~84 % write times reduction and similar accuracy compared with the state-of-the-art ReRAM/PCMlFeFET-based CiM design for HDC encoding, respectively.
The concept of multi-level cell (MLC) enabled by emerging memory device technologies has introduced new opportunities for memory density improvement, including in the cache scenarios with some ...high-endurance technologies. However, the access latency of different bits within an MLC memory cell is inherently nonuniform, which raises challenges in utilizing the MLC technology for low-latency cache. To exploit the access performance of the MLC cache, the key is identifying the hot data blocks and mapping them to fast MLC bits. Prior works perform the hot/cold data management based on block-wise access patterns with considerable hardware overheads. Inspired by the memory hierarchy, this work proposes a new concept of in-cell hierarchical victim cache as embedded memory and systematically presents the cache architecture, operating mechanism, design space exploration, optimizations, and evaluations. By utilizing the slow bits as the victim buffer, lower hit latency with low implementation overheads is achieved. Based on the in-cell victim cache, two optimization techniques, namely selective victim retrieval, and victim-bypassing write (VBW) are proposed, to further improve performance and prolong cache endurance, respectively. Evaluation results show that the MLC victim cache significantly improves the average system performance by 20.2% over conventional MLC cache and achieves 98% performance of the upper bound implemented with 2x memory cells SLC. The proposed VBW also reduces energy consumption by 21% and improves lifetime by over 80%, showing a new promising dimension for future MLC cache design.
This paper proposes low-power design of embedded dynamic random-access memory (eDRAM) using emerging nanoelectromechanical (NEM) relay devices. The motivation of this work is to reduce the standby ...refresh power consumption through the improvement of retention time of eDRAM cells. In this paper, it is revealed that the tunable beyond-CMOS characteristics of emerging NEM relay devices, especially the ultra-high OFF-state drain-source resistance, open up new opportunities with device-circuit co-design. In addition, the pull- in and pull-out threshold voltages are tilled to fit the operating mechanisms of eDRAM, so as to support low-voltage operations along with long retention time. Excitingly, when low-gate-leakage thick-gate transistors are used together, the proposed NEM-relay- based eDRAM exhibits so significant retention time improvement that it behaves almost "nonvolatile". Even if using thin-gate transistors in a 130nm CMOS, the evaluation of the proposed eDRAM shows up to 63x and 127x retention time improvement at 1.0V and 1.4V supply, respectively. Detailed performance benchmarking analysis, along with the practical CMOS- compatible NEM relay model, the eDRAM design and optimization considerations, is included in this paper.
This paper proposes low-power design of embedded dynamic random-access memory (eDRAM) using emerging nanoelectromechanical (NEM) relay devices. The motivation of this work is to reduce the standby ...refresh power consumption through the improvement of retention time of eDRAM cells. In this paper, it is revealed that the tunable beyond-CMOS characteristics of emerging NEM relay devices, especially the ultra-high OFF-state drain-source resistance, open up new opportunities with device-circuit co-design. In addition, the pull-in and pull-out threshold voltages are tilled to fit the operating mechanisms of eDRAM, so as to support low-voltage operations along with long retention time. Excitingly, when low-gate-leakage thick-gate transistors are used together, the proposed NEM-relay-based eDRAM exhibits so significant retention time improvement that it behaves almost "nonvolatile". Even if using thin-gate transistors in a 130nm CMOS, the evaluation of the proposed eDRAM shows up to 63x and 127x retention time improvement at 1.0V and 1.4V supply, respectively. Detailed performance benchmarking analysis, along with the practical CMOS-compatible NEM relay model, the eDRAM design and optimization considerations, is included in this paper.
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