METHOD AND APPARATUS FOR EMULATING AN ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) USING NON-VOLATILE FLOATING GATE MEMORY CELLS

摘要

An emulated EEPROM memory array is disclosed based on non-volatile floating gate memory cells, such as Flash cells, where a small group of bits share a common source line and common row lines, so that the small group of bits may be treated as a group during program and erase modes to control the issues of program disturb and effective endurance. The bits common to be shared source line make up the emulated EEPROM page which is the smallest unit that can be erased and reprogrammed, without disturbing other bits. The memory array is physically divided up into groups of columns. One embodiment employs four memory arrays, each consisting of 32 columns and 512 page rows (all four arrays providing a total 1024 pages with each page having 8 bytes or 64 bits). A global row decoder decodes the major rows and a page row driver and a page source driver enable the individual rows and sources that make up a given array. The page row drivers and page source drivers are decoded by a page row/source supply decoder, based on the addresses to be accessed and the access mode (erase, program or read).