A 64-Tile 2.4-Mb In-Memory-Computing CNN Accelerator Employing Charge-Domain Compute

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Large-scale matrix-vector multiplications, which dominate in deep neural networks (DNNs), are limited by data movement in modern VLSI technologies. This paper addresses data movement via an in-memory-computing accelerator that employs charged-domain mixed-signal operation for enhancing compute SNR and, thus, scalability. The architecture supports analog/binary input activation (IA)/weight first layer (FL) and binary/binary IA/weight hidden layers (HLs), with batch normalization and input-output (IO) (buffering) circuitry to enable cascading, if desired, for realizing different DNN layers. The architecture is arranged as 8× 8=64 in-memory-computing neuron tiles, supporting up to 512, 3× 3× 512-input HL neurons and 64, 3× 3× 3-input FL neurons, configurable via tile-level clock gating. In-memory computing is achieved using an 8T bit cell with overlaying metal-oxide-metal (MOM) capacitor, yielding a structure having 1.8× the area of a standard 6T bit cell. Implemented in 65-nm CMOS, the design achieves HLs/FL energy efficiency of 866/1.25 TOPS/W and throughput of 18876/43.2 GOPS (1498/3.43 GOPS/mm2), when implementing convolution layers; and 658/0.95 TOPS/W, 9438/10.47 GOPS (749/0.83 GOPS/mm2), when implementing convolution followed by batch normalization layers. Several large-scale neural networks are demonstrated, showing performance on standard benchmarks (MNIST, CIFAR-10, and SVHN) equivalent to ideal digital computing.

Original languageEnglish (US)
Article number8660469
Pages (from-to)1789-1799
Number of pages11
JournalIEEE Journal of Solid-State Circuits
Issue number6
StatePublished - Jun 2019

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering


  • Charge-domain compute
  • deep learning
  • hardware accelerators
  • in-memory computing
  • neural networks


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