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. We explore the
modulation of charge on the floating node through both hot-electron
injection and Fowler-Nordheim tunneling, 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 (PDK), and makes the corresponding FG cell designs available
for public use.