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Modeling Series R in an MOS (Active Device) Capacitor ??

J

John Larkin

Jan 1, 1970
0
I'm trying to come up with a model of the series resistance of a
capacitor formed using gate-channel capacitance and with drain-source
merged.

That's cheating. Not nice.

Refer to....

http://www.analog-innovations.com/SED/MOS-CAP-Series-R.pdf

(I'm not very good at conformal mapping of rectangular objects :)

Ideas?

Where on the sheet do you make the connection? The location and
geometry of the connection matter.

Clearly a single resistance will be an imperfect model. Capacitance
near the contact is nearly pure, and capacitance farther away sees
more series R. It's one of those nasty diffusion things.


John
 
J

Jim Thompson

Jan 1, 1970
0
That's cheating. Not nice.



Where on the sheet do you make the connection? The location and
geometry of the connection matter.

Connections: Merged Drain-Source is one connection, Gate Plate is the
other.
Clearly a single resistance will be an imperfect model. Capacitance
near the contact is nearly pure, and capacitance farther away sees
more series R. It's one of those nasty diffusion things.


John

A two-dimensionsal ladder would be OK as a model.

Clearly I'm asking because it's not easy ;-)

I prefer "fingered" structures myself (which model easily, since
they're one-dimensional), but a client is using this without a clue of
the series R effect :-(

...Jim Thompson
 
J

Jim Thompson

Jan 1, 1970
0
I'm trying to come up with a model of the series resistance of a
capacitor formed using gate-channel capacitance and with drain-source
merged.

Refer to....

http://www.analog-innovations.com/SED/MOS-CAP-Series-R.pdf

(I'm not very good at conformal mapping of rectangular objects :)

Ideas?

Thanks in advance!

...Jim Thompson

Square (most common case, L=W) is fine, if it helps the modeling.

...Jim Thompson
 
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