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Cited by 292

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NullHop: A Flexible Convolutional Neural Network Accelerator Based on Sparse Representations of Feature Maps

Open access
Aimar, Alessandro, Mostafa, Hesham, Calabrese, Enrico, Rios-Navarro, Antonio, Tapiador-Morales, Ricardo, Lungu, Iulia-Alexandra, Milde, Moritz B., Corradi, Federico, Linares-Barranco, Alejandro, Liu, Shih-Chii, Delbruck, Tobi·2019·IEEE Transactions on Neural Networks and Learning Systems

Abstract

Convolutional neural networks (CNNs) have become the dominant neural network architecture for solving many state-of-the-art (SOA) visual processing tasks. Even though graphical processing units are most often used in training and deploying CNNs, their power efficiency is less than 10 GOp/s/W for single-frame runtime inference. We propose a flexible and efficient CNN accelerator architecture called NullHop that implements SOA CNNs useful for low-power and low-latency application scenarios. NullHop exploits the sparsity of neuron activations in CNNs to accelerate the computation and reduce memory requirements. The flexible architecture allows high utilization of available computing resources across kernel sizes ranging from 1×1 to 7×7. NullHop can process up to 128 input and 128 output feature maps per layer in a single pass. We implemented the proposed architecture on a Xilinx Zynq field-programmable gate array (FPGA) platform and presented the results showing how our implementation reduces external memory transfers and compute time in five different CNNs ranging from small ones up to the widely known large VGG16 and VGG19 CNNs. Postsynthesis simulations using Mentor Modelsim in a 28-nm process with a clock frequency of 500 MHz show that the VGG19 network achieves over 450 GOp/s. By exploiting sparsity, NullHop achieves an efficiency of 368%, maintains over 98% utilization of the multiply-accumulate units, and achieves a power efficiency of over 3 TOp/s/W in a core area of 6.3 mm2. As further proof of NullHop's usability, we interfaced its FPGA implementation with a neuromorphic event camera for real-time interactive demonstrations.

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Metadata

Authors
Aimar, A., Mostafa, H., Calabrese, E., Rios-Navarro, A., Tapiador-Morales, R., Lungu, I.-A., Milde, M. B., Corradi, F., Linares-Barranco, A., Liu, S.-C., & Delbruck, T.
Venue
IEEE Transactions on Neural Networks and Learning Systems
Published
2019-03
Volume
30
Issue
3
Pages
644-656
ISSN
  • 2162-237X (ISSN-L)
  • 2162-2388
OpenAlex
W2623629680
Cited by
292
References
44
FWCI
18.69
Type
journal article
Language
en
Open access
green

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Aimar, A., Mostafa, H., Calabrese, E., Rios-Navarro, A., Tapiador-Morales, R., Lungu, I.-A., Milde, M. B., Corradi, F., Linares-Barranco, A., Liu, S.-C., & Delbruck, T. (2019). NullHop: A Flexible Convolutional Neural Network Accelerator Based on Sparse Representations of Feature Maps. IEEE Transactions on Neural Networks and Learning Systems. https://doi.org/10.1109/tnnls.2018.2852335

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Semantic Scholar’s data is described in: Kinney, R., et al. (2023). The Semantic Scholar Open Data Platform. arXiv:2301.10140.