A zone-programmed EEPROM with real-time write monitoring for analog data storage

A non-volatile high-precision zone-programmed EEPROM comprising two transistors per cell is proposed. The newly developed memory employs channel hot electron injection and real-time write monitoring during cell programming to achieve automatic write termination without conventional write-verify cycles. A zone programming scheme that effectively suppresses error due to over-writing is also proposed. The new scheme not only enhances programming precision but also improves cell writing speed when compared to conventional single voltage programming schemes. Experimental analyses show that, with the incorporation of this scheme, overwrite errors are reduced to 0.5 mV and 8∼10 bit accuracy for a dynamic range of 2.5 V can be obtained within a write time of 100 μs.