A 0.086 mm$^2$ 12.7 pJ/SOP 64k Synapse 256 Neuron Online Learning Digital Spiking Neuromorphic Processor in 28 nm CMOS
Shifting computing architectures from von Neumann to event based spiking neural networks (SNNs) uncovers new opportunities for low power processing of sensory data in applications such as vision or sensorimotor control. Exploring roads toward cognitive SNNs requires the design of compact, low power and versatile experimentation platforms with the key requirement of online learning in order to adapt and learn new features in uncontrolled environments. However, embedding online learning in SNNs is currently hindered by high incurred complexity and area overheads. In this paper, we present ODIN, a 0.086 mm<inline formula><tex math notation="LaTeX"^2$/tex math>/inline formula> 64k synapse 256 neuron online learning digital spiking neuromorphic processor in 28 nm FDSOI CMOS achieving a minimum energy per synaptic operation (SOP) of 12.7 pJ. It leverages an efficient implementation of the spike driven synaptic plasticity (SDSP) learning rule for high density embedded online learning with only 0.68 <inline formula><tex math notation="LaTeX"\mu$/tex math>/inline formula>m<inline formula><tex math notation="LaTeX"^2$/tex math>/inline formula> per 4 bit synapse. Neurons can be independently configured as a standard leaky integrate and fire model or as a custom phenomenological model that emulates the 20 Izhikevich behaviors found in biological spiking neurons. Using a single presentation of 6k 16 x 16 MNIST training images to a single layer fully connected 10 neuron network with on chip SDSP based learning, ODIN achieves a classification accuracy of 84.5% while consuming only 15 nJ/inference at 0.55 V using rank order coding. ODIN thus enables further developments toward cognitive neuromorphic devices for low power, adaptive and low cost processing.
IEEE Transactions on Biomedical Circuits and Systems