From: mcguire at neurotica.com> > This is very
true. EPROMs store their bits in "floating gates", > which are conductive
areas which are totally surrounded by an > insulating material. Exposure to UV light
causes that insulating > material to become partially conductive, allowing the charge
to drain > from the floating gate...and that charge has to GO somewhere.
Hi
The charge is really small. Once it is connected to the rest
of the chip, it is discharged enough. You don't need to pass
the charge to the outside. I have small eraser that doesn't
even have uniform contact and it erases just fine. In any case, the gate is like a
capacitor. You put a charge
on one side and an equal but opposite charge will exist
on the other side. When the leads are connected together,
there is rarely any static charge left. This is because the ability
to hold charge is related to the capacitance. The capacitance
of an object to the rest of the world is small but across
the plates it is orders of magnitude larger. The same is true
for the floating gate.
The problem is that you are thinking of the charge on the gate
as though it were completely isolated from the rest of the
world. This isn't true or it would be useless to control current
in the transistor. It has to have a relatively large capacitance
to transistor.
Dwight
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