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55nm CMOS Analog Circuit Implementation of LIF and STDP Functions for Low-Power SNNs

Spiking neural networks (SNNs) demonstrate great potentials to achieve low-power computation for AI applications. SNN uses spike trains, instead of binary bit-steams to encode input and output information, therefore, analog implementation of SNN will have more advantages than digital implementation in terms of power consumption and hardware overheads. Leaky Integrate-and-Fire (LIF) and Spike Timing Dependent Plasticity (STDP) models are the two fundamental mechanisms of SNN operation. In this paper, we propose a 55nm analog CMOS implementation of the LIF and STDP functions. Testing results demonstrate that the circuit can closely imitate the behavior of the LIF and STDP mechanisms, while demanding a much lower power consumption (around 1nJ per spike with the pulse width of 0.5ms). The proposed LIF and STDP circuits can be used as building blocks to construct a complete SNN architecture.