I'm approaching to analog layout with Virtuoso XL. I have to realize the layout of a simple current mirror (2 transistors) and, for matching purposes, I'd like to realize it using an inter-digitized (or common centroid) arrangements.
There is a way, in Virtuoso XL, to merge 2 or more instances in order to form an inter-digitated one? It seems to me that, starting from a schematic entry and generating the layout from this source, Virtuoso XL only gives separate instances and the only thing to do is routing them.
Can anyone show me the procedure for activating transistors inter-digitization in Virtuoso XL?
If you need assistance I suggest that you contact Cadence Customer Support and/or your local Field Application Engineer.
Craig Thompson Sr. Technical Leader Technical Field Operations, North America-Central Region 866.225.3138
In reply to Craig Thompson:
Unfortunately I'm using IC 5.1.41, can you suggest me a similar procedure for this release?
In reply to luca magnelli:
You maybe able to use the constraints in a similar way using the Group and/or Symmetry constraints available in VXL to achieve what you want. Reference the IC 5141 Virtuoso Constraint Manager User Guide.
Unfortunately Modgens were not implemented in IC5141 VXL. They were found in the NeoCell product. The majority of the NeoCell 3.4 features including Modgens, Analog Placer, Cell Planner and Constraints/Constraint Manager were integrated into IC61.
An automatic interdigitation algorithm is pretty complex unless you use the natural capabilities of abutment in aligningthe cells. Using dbMoveFig or rodAlign on a cell does not trigger abutment during a SKILL program but if you follow the move/align command immediately with hiUpdate(), the abutment/spacing will automatially trigger. Thus, you are spared some of the messy calculations for the pcell parameters as the tool will automatically send the abutment program the correct values. Of course, your abutment program has to be working correctly.
I do not have the algorithm I used before Cadence bought NeoLinear as it was hard to maintain and NeoCell's capabilities were better (in IC6.1 especially).