An analog floating-gate memory in a standard digital technology

In this paper we present a simple CMOS analog memory structure using the floating gate of a MOS transistor. The structure is based on a special but simple layout which allows significant tunneling at relatively low voltage levels. The programming of the memory is achieved using the standard Fowler-Nordheim tunneling and is implemented in a standard digital CMOS process with only one polysilicon layer. A simple on-chip memory driver circuit is also presented. Experimental results from test chips fabricated in a standard 2-micron CMOS process show six orders of magnitude dynamic range in current for subthreshold operation.