i A PHYSICAL IMPLEMENTATION WITH CUSTOM LOW POWER ...

7.0 EEPROM CIRCUIT DESIGN
EEPROM (Electrically Erasable/Programmable Read Only Memory) is a non-volatile memory
device which has the capability to be read like an ordinary ROM as well as to be erased
/programmed electrically to a new data value that needs to be stored. The fundamental
component in the EEPROM cell is the FLOTOX (Floating Gate Tunnel Oxide) transistor. The
following sections describe the implementation of the EEPROM design in a 0.35um process.
7.1 EEPROM CELL
The FLOTOX transistor is a device, which can be used to store a “bit” value. The EEPROM cell
operates by changing the threshold voltage of the FLOTOX transistor [19]. When the transistor’s
threshold voltage is increased, the transistor does not conduct for normal applied voltages and is
said to be erased. When the transistor’s threshold voltage is reduced, the transistor begins to
conduct even for a zero gate to source voltage and is said to be written. The structure of the
FLOTOX shown in Figure 7-1 shows the gate oxide and tunnel oxide regions of the transistor.
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