A Self-referenced and regulated sensing solution for PCM with OTS selector

Abstract

Phase change memory (PCM) device associated with Ovonic Threshold Switch (OTS) selector is a proven solution to fill the gap between DRAM and mass storage. This technology also has the potential to be embedded in a high-end microcontroller. However, programming and reading phases efficiency is directly linked to the selector's leakage current and the sneak-path management. To tackle this challenge, we propose in this paper, a new sense amplifier able to generate an autoreference taking into account leakage current of unselected cell, including a regulation loop to compensate voltage drop due to reading current sensing. This auto-referenced sense, built on the charge-sharing principle, is designed on a 28nm FDSOI technology and validated through extensive Monte-Carlo and corner cases simulations. From the simulation results, our sense amplifier is demonstrated to be robust for an ultra-large range of sneak-path current and consequently for a large range of memory array size, suitable for embedded memory in high-end microcontroller.