DEF import issue

stolbikov

Hello!
I faced with the following issue:
When I import DEF file, to display topology KLayout uses dbu-to-microns scale factor from "UNITS DISTANCE MICRONS 2000 ;" statement of
imported DEF file. This looks correct. But then I select some shape properties and check "Coordinates in database units" button. And all dimentions and coordinates are recalculated based on "Layout DBU" coefficient defined in LEF/DEF section of Technology Manager for selected technology. And this scale factor can be different than in DEF file. So, I'm getting incorrect dimentions and coordinates in database units.
Why KLayout uses scale factors from different places?
What is the purpose of "Layout DBU" in technology settings? Is scale factor from DEF file not enough?

Matthias

@stolbikov "Layout DBU" is the "target database unit". While DEF may specify a database unit of 10nm, the GDS database unit typically is specified as 1nm or smaller to provide a precision reserve for further computations.

That's why the target DBU is a separate and technology-driven parameter.

Matthias

stolbikov

@Matthias OK, I got it. But in this case the checkbox description "Coordinates in database units" is quite confusing because there is no understanding what database is meant by. In my case I decided that after this checkbox is enabled I'll get coordinates in DEF database units.