ywguo
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Hi, Paul,
You are right. Any metal lines is forbidden under the MIM caps in the design rule. And I have never put dummy metal under the MIM caps, because I thought the behaviour of floating metal lines are not described clearly. I am not sure whether it couples with other signal lines or function as many antennas. ???
As to using the 3rd layer from top as shielding, I have never thought of that. If no floating metal lines is put under the MIM caps, is the 3rd layer more effective than N-well shielding if we don't consider the parasitic capacitance?
Thanks
Yawei Guo
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