A coupled electro-thermal kinetic state variable model for GST467 phase change synapses

To achieve energy-efficient neuromorphic hardware, there is a need for compact and physics-based models that can model the coupled electrical, thermal, and phase transition dynamics in analog phase-change synapses. The paper focuses on the novel state-variable model that is specifically designed to capture the GST467 phase-change synapse dynamics by coupling the electro-thermal-kinetic dynamics with the crystalline fraction evolution and a localized thermal memory variable. Unlike other compact models based on threshold logic or binary PCM, the proposed model allows for gradual, repeatable, and variability-resilient conductance modulation in response to the same sub-volt programming pulses. The proposed model is implemented in MATLAB and is computationally efficient. Multi-level operation with more than 8 stable conductance states is achieved in the microampere current regime, and Monte Carlo simulations show that the synaptic weight precision is robust against ± 10% variability of the model parameters. Owing to its physical interpretability, scalability, and low computational overhead, the proposed framework provides a practical and extensible compact-modeling platform for large-scale neuromorphic crossbar simulations.