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Design >> Analog Design >> MOM Cap Layout Connection
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Message started by hacksgen on Jun 24^th, 2012, 1:04pm

Title: MOM Cap Layout Connection
Post by hacksgen on Jun 24^th, 2012, 1:04pm

Hello everyone,

I have a very question regarding MOMCAP in UMC 90nm process. I have not used MOMCAP for my design till now and I wish to try them out. I see that the symmettric MOMCAP in schematic has three terminals Plus, minus and bulk. In the layout I see only the two terminals Plus and Minus. I dont see a Bulk connection as such. Is the bulk connection in MOMCAP same as that for PMOS. That is should I draw a Nwell around the MOMCAP and connect it to VDD or is it something different.

Please let me know how the bulk connection is to be made in the layout for MOMCAP.

I am using the guard ring option around the momcaps.

Assura LVS gives me a Malformed device error for the MOMCAP when I run it only on a layout containing just the momcap and some pins.
It does not recognise the MOMCAP bulk.

Any Help would be appreciated.

Regards

Title: Re: MOM Cap Layout Connection
Post by aaron_do on Jun 24^th, 2012, 10:24pm

hi,

the bulk refers to the substrate, so it should be the connection to the guard rings surrounding the MOM.

regards,
Aaron

Title: Re: MOM Cap Layout Connection
Post by hacksgen on Jun 25^th, 2012, 12:42am

Hi aaron,

Thanks for the reply.
My current test schematic consists of the MESH MOMCAP which has five terminals. Two plus and two minus alongwith a bulk terminals.
In the layout I create the MESH MOMCAP and attach five pins to the capacitor. THe bulk pin as you said , I placed on the gaurd ring surrounding the MOMCAP.

I run assura but it still does not recognise the bulk connection at all.. It always gives me the malformed_device_MOM_MESH_SY_PSUB error.

Have I done something wrong here?.