Abstract—The grand challenge of neuromorphic computation
is to develop a flexible brain-like architecture capable of a
wide array of real-time applications, while striving towards the
ultra-low power consumption and compact size of the human
brain—within the constraints of existing silicon and post-silicon
technologies. To this end, we fabricated a key building block of a
modular neuromorphic architecture, a neurosynaptic core, with
256 digital integrate-and-fire neurons and a 1024×256 bit SRAM
crossbar memory for synapses using IBM’s 45nm SOI process.
Our fully digital implementation is able to leverage favorable
CMOS scaling trends, while ensuring one-to-one correspondence
between hardware and software. In contrast to a conventional
von Neumann architecture, our core tightly integrates computation
(neurons) alongside memory (synapses), which allows us
to implement efficient fan-out (communication) in a naturally
parallel and event-driven manner, leading to ultra-low active
power consumption of 45pJ/spike. The core is fully configurable
in terms of neuron parameters, axon types, and synapse states
and is thus amenable to a wide range of applications. As an
example, we trained a restricted Boltzmann machine offline to
perform a visual digit recognition task, and mapped the learned
weights to our chip.