Noisy neuromorphic neurons with RPG on-chip noise source

Abstract

Noise can play beneficial roles in neural network systems from biology to neuromorphic computing through stochastic resonance, averaging signals, and other mechanisms. To achieve the benefits of noise in neuromorphic circuits, we propose a random pulse generator(RPG) as a source of noise and describe its implementation in neuromorphic circuits. The RPG includes three components: an LED, a wave guide, and a single-photon avalanche diode(SPAD). The LED will generate photons in Poisson-distributed time intervals with Gaussian-distributed amplitude. Through a wave guide, the SPAD senses the photons and generate uV wavelength random pulses. The noise can be implemented in a discrete manner by connecting to an amplifier and in a continuous manner by connecting to a current mirror. The design was simulated using CMOS 180nm SPICE models. The generated variable signals are used in different parts of a BioRC neuromorphic neuron to implement a noisy neuron following different neurological findings. The noisy neuron's random postsynaptic potential(PSP), along with mechanisms to support stochastic resonance, noise inhibition and noise-forced spiking were demonstrated.