Virtuoso XL Layout Editor User Guide

Editing Your Layout with Virtuoso XL Layout Editor

same abutment class and different nets are pushed apart a distance equal to the maximum values of the two vxlInstSpacingRule pins. To control the abutment spacing set the vxlInstSpacingRule to string abutFunction.

Note: The abutFunction is not the name of your custom abutment function, but is the property that is set to the name of your abutment function.

dbReplaceProp(sObj~>dbId "abutFunction" "string" "myCustomAbutmentFunction")

dbReplaceProp(sObj~>dbId "vxlInstSpacingRule" "string" "abutFunction")

You can write your own spacing function for the two instances involved. For example, myCustomSpacingFunc ( )is to be called in the body of the user defined abutment function (abutFunction). The myCustomSpacingFunc ( ) must return a float value to be effective.

There are two numbers passed to the abutment function, the connection condition (1, 2, or 3) and the abutment event (1, 2, 3, or 4). The connection condition (3) is for different nets. The sequence for non abuttable pins should be the same as for abuttable. The calling of the abutment function for adjusting the pcells (event 2) and then one to calculate the spacing of the resultant reference edges (event 4). This allows you to adjust the well or isolation on the pcell and then space the devices based on the reference edges.

To get the spacing offset when pins are on different nets add the following case in your custom abutment function.

(4

if(instA~>w > 3.0 && instB~>w > 3.0 then

result = 3

else

result = 1

)

);; end of case 4

Using Interactive Device Abutment

To abut two devices that are set up for abutment, follow these steps.

1.From the layout window, choose Options – Virtuoso XL.

The Virtuoso XL Options form appears.

2.Ensure that the Auto Abutment and Connectivity Extractor options are turned on.

3.Move an instance so that one of its instance pins touches the instance pin of another instance.