Open‐source floating‐gate cell for analogue synapses

Abstract The floating‐gate transistor is commonly employed as a non‐volatile memory device, leveraging a floating node at its gate to store electrical charge over extended periods. This stored charge effectively alters the threshold voltage of the transistor. Utilizing standard CMOS technologies, floating‐gate transistors can be designed and fabricated using conventional CMOS processes. This study focuses on characterizing the performance of a PMOS‐based floating‐gate transistor, specifically fabricated using the open‐source Skywater 130 nm process. The modulation of charge on the floating node is explored through both hot‐electron injection and Fowler–Nordheim tunnelling, providing insight into the resolution of these programming mechanisms. Additionally, the study includes a preliminary analysis of the retention time of the programmed charge in these devices. This work contributes to the open‐source electronics community by detailing the design and programming techniques of floating‐gate transistors developed with an open‐source process design kit, and makes the corresponding FG cell designs available for public use.