What are Filler Cells for in Cadence SOC Encounter?

[Prasanna Kumar]

Regarding Filler Cells

Hi all,

I am working with Cadence SOC Encounter. In that we have an option of adding filler cells. I shall be greatful if some one gives me the details as why we shud add these this filler cells

1.Why we actually need filler cells in the Design

Thanks in Advance

 

[Raptor]

Re: Regarding Filler Cells

when performing automatic place and route using standard cells there will be discontinuity in power,ground and diffusion layers because all the cells will not be abutting. Fillers cells are inserted in between to get the continuity back.

hope this helps.

 

[Prasanna Kumar]

Re: Regarding Filler Cells

Hi

I didnot get these lines " there will be discontinuity in power,ground and diffusion layers because all the cells will not be abutting "

Could u explain this in some detail please....

At what stage in the design do we have to add filler cells,

1. either after placing
2. of after the detailed routing

After having added filler cells into the design are there any chances there is increase in congestion ??

Correct me if I am wrong.

 

[Thinkie]

Re: Regarding Filler Cells

filler cells are... eerr... nothing... just a special pattern that goes into unused cell locations, and is not something really to worry about.

 

[Raptor]

Re: Regarding Filler Cells

IN standard cells APR flow:
the cells in the design are placed on the row. To make sure that
each cells gets power and ground connection, the cells are abutted
together so that the VDD and VSS terminal of neighbouring cells
short together. This makes it possible to tap power only at one point
anywhere in the row.
but it is virtually impossible that you will not have gaps between standard cells,
which means there will be discontinuity in VDD and VSS. This is overcome by
adding filler cells.

 

[Prasanna Kumar]

Re: Regarding Filler Cells

Hi,

So Filler cells are used to observe the continuity in the design. Thanks a lot

Prasanna

Added after 5 minutes:

Hi,

Thanks a lot for the pic u have given.Can u send me some link regarding the filler cells, I ll browse the net to get some more info regarding them.

Added after 1 minutes:

HI

Thanks a lot for the pic u have sent.

 

[chinkooi]

Re: Regarding Filler Cells

Filler cells are empty cells that provide nwell continuity.