I am trying to implemen t a divider using macro cells with encounter. The LEF of a macro cell is attached.The macro cell consists of two standard cell rows sharing the gnd! in the middle. So the macro cell starts with power (vdd!) on top,has ground (gnd!) in middle and ends with power (vdd!) at the bottom.
With encounter (versions mainly 9.1 and also 10.1) I commit floorplan and I do specialRoute to get gnd! and vdd! rails. Than I perform a standard cell placement.
My problem is that the cell is auto placed at a gnd! - vdd! - gnd! combination whereas it uses vdd! - gnd! - vdd! combination.I try to move slitly the macro (i.e to the right) and when I release it, it is auto moved to the row below as to use the proper vdd! - gnd! combination. So I do not think that it is a pin problem.
The problem does not occuse when the macro has gnd! at the bottom (and not in the middle).
Why is encounter showing me this behaviour?
Thanks for your help (to which I am in desperate of),My appologies for consuming your time,
If this is a double-height cell then you should have double-height rows defined in your floorplan which align properly to the single-height rows so the power rails align properly. For example, typically you will have two site definitions:
SIZE 2.8 BY 2.52 ;
CLASS CORE ;
SYMMETRY Y ;
SIZE 2.8 BY 5.04 ;
SYMMETRY Y ;
Specify Floorplan will then automatically create the single and double-height rows if instances in the netlist use these sites.
In reply to wally1:
Thanks for your help. It was exactly what I needed to do.
I have a similar problem except that my cell has gnd-vdd-gnd power lines and encounter is placing them in vdd-gnd-vdd configuration. I have specified the double row site as stated. Is there a way to fix this?
In reply to jinghuayang: