i A PHYSICAL IMPLEMENTATION WITH CUSTOM LOW POWER ...

7.2.6 Sense Amplifier
Figure 7-17: Power Multiplexer Schematic
The sense amplifier is the circuit that senses the voltage at the output of the EEPROM cell during
a read operation. The design of the sense amplifier is based on the voltage sensing scheme as
proposed by [24]. Under erase or program conditions, signal C1 is asserted pulling the source of
the FLOTOX transistor to ground. C2 is asserted under normal conditions. During a read
operation, C1 gets de-asserted rising the voltage at node “ee_cs” to the supply Vdd. The control
voltage is set to the supply voltage Vdd. The wordline is enabled, effectively turning on the
select transistor and the control gate transistor. If the FLOTOX transistor is programmed, the
voltag e at the gate terminal
of the FLOTOX transistor, causes the transistor to conduct, raising
the voltage of the bit line from 0V to Vx. The value of Vx dpends on the wordline voltage. If the
voltage at the wordline is high because of use the of wordline boosters, the select transistor
would not incur a Vth drop across it. Otherwise the voltage at the bit line would be reduced by
the threshold voltage drop across the select transistor.
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