Deep convolutional neural networks (CNNs) have achieved state-of-the-art performance in a wide range of applications. However, deeper CNN models, which are usually computation consuming, are widely required for complex artificial intelligence (AI) tasks. Though recent research progress on network compression, such as pruning, has emerged as a promising direction to mitigate computational burden, existing accelerators are still prevented from completely utilizing the benefits of leveraging sparsity due to the irregularity caused by pruning. On the other hand, field-programmable gate arrays (FPGAs) have been regarded as a promising hardware platform for CNN inference acceleration. However, most existing FPGA accelerators focus on dense CNN and cannot address the irregularity problem. In this article, we propose a sparsewise dataflow to skip the cycles of processing multiply-and-accumulates (MACs) with zero weights and exploit data statistics to minimize energy through zeros gating to avoid unnecessary computations. The proposed sparsewise dataflow leads to a low bandwidth requirement and high data sharing. Then, we design an FPGA accelerator containing a vector generator module (VGM) that can match the index between sparse weights and input activations according to the proposed dataflow. Experimental results demonstrate that our implementation can achieve 987-, 46-, and 57-imag/s performance for AlexNet, VGG-16, and ResNet-50 on Xilinx ZCU102, respectively, which provides 1.5x-6.7x speedup and 2.0x-6.0x energy efficiency over previous CNN FPGA accelerators.
28 March 2014 in IEEE Transactions on Circuits and Systems I: Regular Papers
The high leakage current has been one of the critical issues in SRAM-based Field Programmable Gate Arrays (FPGAs). In recent works, resistive non-volatile memories (NVMs) have been utilized to tackle the issue with their superior energy efficiency and fast power-on speed. Phase Change Memory (PCM) is one of the most promising resistive NVMs with the advantages of low cost, high density and high resistance ratio. However, most of the reported PCM-based FPGAs have significant active leakage power and reliability issues. This paper presents a low active leakage power and high reliability PCM based non-volatile SRAM (nvSRAM). The low active leakage power and high reliability are achieved by biasing PCM cells at 0 V during FPGA operation. Compared to the state-of-the-art, the proposed nvSRAM based 4-input look up table (LUT) achieves 174 times reduction in active leakage power and 15000 times increase in retention time. In addition, the proposed nvSRAM-based FPGA system significantly accelerates the loading speed to less than 1 ns with 2.54 fJ/cell loading energy.
Learning scheme is the key to the utilization of spike-based computation and the emulation of neural/synaptic behaviors toward realization of cognition. The biological observations reveal an integrated spike time- and spike rate-dependent plasticity as a function of presynaptic firing frequency. However, this integrated rate-temporal learning scheme has not been realized on any nano devices. In this paper, such scheme is successfully demonstrated on a memristor. Great robustness against the spiking rate fluctuation is achieved by waveform engineering with the aid of good analog properties exhibited by the iron oxide-based memristor. The spike-time-dependence plasticity (STDP) occurs at moderate presynaptic firing frequencies and spike-rate-dependence plasticity (SRDP) dominates other regions. This demonstration provides a novel approach in neural coding implementation, which facilitates the development of bio-inspired computing systems.
21 June 2022 in IEEE Transactions on Circuits and Systems II: Express Briefs
Polynomial multiplication is the key and time-consuming operation among various operators in Post-Quantum Cryptography (PQC), which aims to find quantum-resistant algorithms to prevent attacks launched by quantum computers. Number Theoretic Transform (NTT) is an efficient algorithm that can accelerate the polynomial multiplication from $\mathcal {O}(n^{2})$ to $\mathcal {O}(nlog(n))$ . In this brief, we present a pipelined NTT (PipeNTT) hardware architecture in FPGA to achieve high throughput with fewer hardware resources. The dataflow and the butterfly unit are optimized to minimize the latency. To fulfil the proposed dataflow, a Block RAM (BRAM) based reordering unit is designed to further reduce the hardware resource. Moreover, our architecture can also be applied to Inverse-NTT (INTT). Compared to state-of-the-art parallel designs, our design achieves a 30% lower area-time product with 3x less memory space requirement.
A new methodology for manipulating transient‐amorphous states of phase‐change memory (PCM) materials is reported as a viable means to boost the speed, yet reduce the power consumption of PC memories, and is applicable to new forms of PCM‐based neuromorphic devices. Controlling multiple‐pulse interactions with PC materials may provide an opportunity toward developing a new paradigm for ultra‐fast neuromorphic computing.
27 July 2020 in IEEE Transactions on Cognitive and Developmental Systems
The epileptic detection with Electroencephalography (EEG) has been deeply studied and developed. However, previous research gave little attention to the physical appearance and early onset warnings of seizure. When a seizure occurs, electrodes near the epileptic foci will exhibit significantly fluctuating and inconsistent voltages. In this paper, a novel approach to epileptic detection based on the Hierarchy Graph Convolution Network (HGCN) structure is proposed. Multiple features of time or frequency domains extracted from the raw EEG signals are taken as the input of HGCN. The topological relationship between every single electrode is utilized by HGCN. The Tree Classification (TC) and Preictal Fuzzification (PF) are proposed to adapt both multi-classification tasks and refine-classification tasks. Experiments are performed on the CHB-MIT and TUH datasets. Compared with the state-of-the-art, our proposed model achieves a 5.77% improvement of accuracy on the CHB-MIT dataset, and an improvement of 2.43% and 19.7% for sensitivity and specificity on the TUH dataset, respectively.