Analog circuits have proven to be a reliable medium for neuromorphic architectures in silicon, capable of emulating parts of the brain’s computational processes. Information in the brain is shared between… Click to show full abstract
Analog circuits have proven to be a reliable medium for neuromorphic architectures in silicon, capable of emulating parts of the brain’s computational processes. Information in the brain is shared between neurons in the form of spikes, where a neuron’s soma emits a voltage signal after integrating multiple synaptic input currents. To preserve the quality of this information in a rate-based protocol, it is important that a post-synaptic neuron is able to adapt its firing rate to some desired or expected rate, especially in a noisy environment. This paper presents an analog Izhikevich neuron circuit and a proof-of-concept tuning algorithm that adjusts the neuron’s spike rate using proportional feedback control. The neuron circuit is implemented using discrete surface-mount components on a custom printed circuit board, and its output spike pattern is modified by adjusting one of the neuron’s four voltage parameters. Adjusting the voltage parameters gives a neuromorphic system designer the ability to calibrate these silicon neurons in the presence of noise or component imperfections, ensuring a baseline configuration where all neurons exhibit the same, expected spike response given the same input.
               
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