Low Cost Convolutional Neural Network Accelerator Based on Bi-Directional Filtering and Bit-Width Reduction

Woong Choi, Kyungrak Choi, Jongsun Park

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


This paper presents a low-area and energy-efficient hardware accelerator for the convolutional neural networks (CNNs). Based on the multiply-accumulate-based architecture, three design techniques are proposed to reduce the hardware cost of the convolutional computations. First, to reduce the computational cost of convolutions, an adaptive bit-width reduction combined with near-zero skipping is proposed based on differential input method (DIM). The DIM-based design technique can reduce 62.5% of operation bit-width and improve 17.0% of activation sparsity with almost ignorable CNN accuracy degradation. Second, it has been found that adopting a bi-directional filtering window in a CNN accelerator can considerably reduce the energy for data movement with a much smaller number of memory accesses. To expedite the bi-directional filtering operations, we also propose a bi-directional first-input-first-output (bi-FIFO). With SRAM bit-cell layout manner, the proposed bi-FIFO facilitates fast data re-distribution with area and energy efficiency. To verify the effectiveness of the proposed techniques, the AlexNet accelerator has been designed. The numerical results show that the proposed adaptive bit-width reduction scheme achieves 34.6% and 58.2% of area and energy savings, respectively. The bi-FIFO-based accelerator also achieves 32.8% improved processing time.

Original languageEnglish
Pages (from-to)14734-14746
Number of pages13
JournalIEEE Access
Publication statusPublished - 2018 Mar 14


  • Deep neural network
  • FIFO
  • accelerator
  • activation sparsity
  • convolutional neural network
  • energy efficiency
  • line buffer
  • quantization

ASJC Scopus subject areas

  • Computer Science(all)
  • Materials Science(all)
  • Engineering(all)


Dive into the research topics of 'Low Cost Convolutional Neural Network Accelerator Based on Bi-Directional Filtering and Bit-Width Reduction'. Together they form a unique fingerprint.

Cite this