Displaying shapes limit in layout view

Hi everyone, have anyone encountered some layout displaying limit during instancing cells and viewing? The problem is like below

When I instanced few cells, no matter from python script or GUI, if I only show top level, it can show correctly

When change the display mode to increase 1 level of Hierarchy, only four cell displayed, the fifth is missing cannot be displayed or select from GUI. It seems it can only display 4 instances

it there any setting I can do to eliminate this problem?

Another problem is when I trying to instance the 6th cell, the displayed cell is not at the cursor position, but shift to other positions that I cannot select after instance, as shown below.

I am using the Klayout 0.27.9. windows 64 bit.


  • @wishalpha Such things may happen if you exceed the coordinate limits of GDS or you are using extreme scale factors.

    So please check:

    • Do your cell instances used scale factors?
    • What is your database unit and overall layout dimensions?

    For a database unit of 0.001 µm the overall layout dimensions are confined to about -2 to 2 meters. For smaller DBUs these dimensions get smaller accordingly.


  • @Matthias , Thanks for your explanation. I am not using scale factors for the cell instance, but I am using a small (0.01 nm) DBU and hence the layout dimension will be -2 to 2 cm? each my block is 5mm in width which result in maximum 4 units?

    another question is when I flatten all the instances, It will display currently, are there any overall layout dimensions limit when I flatten it? or the flatten will change the DBU I have used for the drawing?


  • Yes, exactly. With 0.01nm GDS files can only represent -2 to 2cm of area. So four 5mm blocks exceed the available dimension space.

    Flatten does not help. It's an intrinsic limit of the coordinate arithmetic with default 32bit coordinates.

    KLayout can be built with 64bit coordinate support which will give you a much larger space, but then you can only save to OASIS. If you want to try: a Windows regular build is available on the master branch with 64bit coordinates here: https://www.klayout.org/downloads/master/windows/klayout-master-win64-c64-install.exe

    However, I wonder what sense it makes to choose 0.01nm. A single atom is about ten times larger, so there is no physical way to represent such small increments. At least with conventional condensed matter. I don't think you are building chips from Neutron star material, are you?


Sign In or Register to comment.