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i A PHYSICAL IMPLEMENTATION WITH CUSTOM LOW POWER ...

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1. EEPROM cell<br />

2. Sense Amplifier<br />

3. High Voltage Generator Using Charge Pump<br />

4. Ramp Generator<br />

5. Word Line Level shifter<br />

6. Column Latch for the bit lines<br />

7. Power multiplexer<br />

EEPROM Cell<br />

Practical implementation of the EEPROM requires a memory process design kit with<br />

FLOTOX transistor models. In the absence such a design kit, EEPROM macromodels which<br />

model the DC and transient characteristics can be used to simulate the EEPROM. The EEPROM<br />

model used in the design has been based on the macromodel described in [21].<br />

Macromodel Description<br />

The macromodel description is entirely based on the model proposed by the paper [21].<br />

The Figure 7-10 shows the circuit schematic of the macromodel description. Transistor M1 is an<br />

NMOS transistor. The Fowler-Nordheim tunneling current is modeled as a voltage-controlled<br />

current source GFN. The value of GFN is given by the expression shown in Equation 7-1 [21].<br />

V fg −Vt<br />

( V fg −Vt<br />

) ttun<br />

= A α<br />

. exp( −β<br />

t t<br />

V −V<br />

GFN tun<br />

tun<br />

Equation 7-1: Fowler-Nordheim Tunneling Current<br />

124<br />

tun<br />

fg<br />

t<br />

)

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