Memory Devices: Part II – Nonvolatile Memories

The first section introduces the classification and illustrates the general features of non-volatile memories. In the section “Read-Only Memory”, the ROM circuit functions are illustrated. The section “Electrically-Programmable Read Only Memory” addresses the structure and operation principles of the EPROM cell, along with its main working issue, namely: reliability. The following section is devoted to the description of the structural and functional properties of the EEPROM. In the next section, the architectural options and the functional properties of the flash memory arrays are discussed along with reliability issues. The final section addresses a number of memory concepts which are still within a development stage and have not emerged as real products yet, such as the magnetic RAM, the ferroelectric RAM and phase-change memory.