The Floating Gate Transistor
EEPROM and flash memory cells use a transistor with a floating gate that holds a charge. When charged, the action of the control gate is impeded, and the charged/uncharged state determines the 0 or 1 content of the bit.
The Erase Circuit
The floating gate transistor stores the charge, and a regular MOS transistor is used to erase it. Most EEPROMs are byte erasable with one MOS transistor for every eight floating gate transistors. Flash memory uses only one MOS transistor to erase an entire block of floating gate transistors.
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