Alexander Neckar, Sam Fok, Ben V. Benjamin, Terrence C. Stewart,
Nick N. Oza, Aaron R. Voelker, Chris Eliasmith, Rajit Manohar, and Kwabena Boahen
Braindrop is the first neuromorphic system
designed to be programmed at a high level of abstraction.
Previous neuromorphic systems were programmed at
the neurosynaptic level and required expert knowledge of
the hardware to use. In stark contrast, Braindrop's computations
are specified as coupled nonlinear dynamical systems
and synthesized to the hardware by an automated procedure.
This procedure not only leverages Braindrop's fabric
of subthreshold analog circuits as dynamic computational
primitives but also compensates for their mismatched and
temperature-sensitive responses at the network level. Thus,
a clean abstraction is presented to the user. Fabricated in
a 28nm FDSOI process, Braindrop integrates 4096 neurons
in 0.65 mm2. Two innovations--sparse encoding through analog
spatial convolution and weighted spike-rate summation
though digital accumulative thinning--cut digital traffic drastically,
reducing the energy Braindrop consumes per equivalent
synaptic operation to 381 fJ for typical network configurations.