[SOLVED] AMS design rules(0.35um) : Understadning "Geometric relation"

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Hi,
I have trouble in understanding "Geometric relations" section in AMS design rules document.It is mentioned for example like

'A extension of B EnAB := distance inside_A - outside_B (A may intersect B)'

what is 'distance inside_A' and 'outside_B' ???? and how it should be interpreted??

I have attached this section below.Please help me to understand

Thanks in advance

 

ghegde said:
'A extension of B EnAB := distance inside_A - outside_B (A may intersect B)'

what is 'distance inside_A' and 'outside_B' ???? and how it should be interpreted??
Click to expand...

a shape A inside another shape B (A can be totally inside B, or may intersect B):

Inside B , all ("outside") edges of A must have a min. distance (=spacing) to B's ("inside") edges (not where they are intersecting of course, if so, but to opposing ("inside") edges of B).
 

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Thanks erikl for the reply
I am just curious to know which scenario causes this.Whether Metal1 and Metal2 overlap(without a via in between) is an example?
 

A good example of "A enclosure of B" would be with a poly1-poly2 capacitor. The edges of poly1 would have to overlap the edges of poly2 by a specified amount. You also make a capacitor in this manner with metal1 and metal2.
 
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    ghegde

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erikl said:
This concerns only shapes A & B on the same layer.
Click to expand...

That may be true for some specific / special case, but I have
seen compound rules like "N+ extension of poly in direction
of gate" - intent being to force an overlap that exceeds
the litho tolerances, where you want full uniform coverage
of something by something-else.

In fact, shapes on the same layer merge, so I think the
extension rule is not meaningful for same-layer polygons.
 
dick_freebird said:
In fact, shapes on the same layer merge, so I think the
extension rule is not meaningful for same-layer polygons.
Click to expand...

dick_freebird is right: I've withdrawn my above statement.

Just min. spacing rules can be valid for same layer shapes.
 

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