Impact of Parasitic Capacitance on Neuromorphic Neuron Circuits

In this paper, the impact of the parasitic parameters of wires in a package on performance of neuron circuits is studied with consideration of neural information encoding characteristics. The H-H neuron and the Izhikevich neuron are used for their simple structure and good biophysics realistic. One of neural information codes, which is called S-Space Coding, is selected as the major indicator of the neuron's performance. A simplified T-Type transmission line is applied to describe the parasitic parameters of wires in package. A set of pulse-width modulation signal is used as stimulations in numerical studies. According to input and output, S-Space symbol sequences of selected neurons can be calculated. By analyzing the symbol sequence, this work finds that the wire resistance may block input signal to neurons. An input port circuit is needed for, instead of connecting input end and neurons with wires directly. The parasitic capacitance introduces a significant delay on output spikes. With the help of S-Space coding, parasitic capacitance has little effect on neural information.