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
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.
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.