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

Feb 04, 2005 3 Replies

That's cheating. Not nice.

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

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....



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



Ideas?



Thanks in advance!



...Jim Thompson



-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

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| 1962 | I love to cook with wine. Sometimes I even put it in the food.



Connections: Merged Drain-Source is one connection, Gate Plate is the other.

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

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.

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

...Jim Thompson

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.

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