Change the cell name in GDS file

When exporting GDS file, the name of the cell will be set default by the class name of the cell. For instance, in the Straight component, we define class Straight and by library += Straight() and fp.export_gds(library) method we can get a GDS file with a Straight cell.

class Straight(fp.IWaveguideLike, fp.PCell):
...

if __name__ == "__main__":
   from gpdk.util.path import local_output_file

   gds_file = local_output_file(__file__).with_suffix(".gds")
   library = fp.Library()

   TECH = get_technology()

   library += Straight()
   fp.export_gds(library, file=gds_file)

To change the name of the cell, the simplest way is to add .with_name("{your_name") after adding class to fp.Library.

class Straight(fp.IWaveguideLike, fp.PCell):
...

if __name__ == "__main__":
   from gpdk.util.path import local_output_file

   gds_file = local_output_file(__file__).with_suffix(".gds")
   library = fp.Library()

   TECH = get_technology()

   library += Straight().with_name("test_name")
   fp.export_gds(library, file=gds_file)

Cell naming rules

Besides changing the cell name from .with_name("{your_name") function, here we provide some advanced methods to implement the cell name as one of the parameters in the PCell.

1. Cell name with default name prefix

   The first method doesn’t add any name parameter to the PCell, however, fp.PCell has already a built-in parameter name so it can also be used since the PCell WithDefaultNamePrefix is inherited from fp.PCell.

   • library += WithDefaultNamePrefix(size=10): The cell name will use the class name as prefix.

     cell name : WithDefaultNamePrefix

   

   • library += WithDefaultNamePrefix(name="N1", size=20): N1 is added after the class name.

     cell name : WithDefaultNamePrefix_N1

   

   • library += WithDefaultNamePrefix(size=30).with_name("N1"): N1 overwrite and used as the cell name.

     cell name : N1

   

   class WithDefaultNamePrefix(fp.PCell):
       size: float = fp.FloatParam()
   
       def build(self) -> Tuple[fp.InstanceSet, fp.ElementSet, fp.PortSet]:
           insts, elems, ports = super().build()
           TECH = get_technology()
           elems += fp.el.Rect(center=(0, 0), width=self.size, height=self.size, layer=TECH.LAYER.M1_DRW)
           return insts, elems, ports
   
   # gds cell name: WithDefaultNamePrefix, using class name as prefix
   library += WithDefaultNamePrefix(size=10)
   # gds cell name: WithDefaultNamePrefix_N1, using class name as prefix
   library += WithDefaultNamePrefix(name="N1", size=20)
   # gds cell name: N1, force to use "N1" as cell name
   library += WithDefaultNamePrefix(size=30).with_name("N1")
   

2. Cell name with blank name prefix

   The second method is defining a name parameter fp.NameParam and setting the prefix to a blank name. This allow users to export the cell name without the class name prefix when using name parameter of the PCell (It overrides the name parameter in fp.PCell).

   • library += WithBlankNamePrefix(size=40): The cell name will use the class name as prefix.

     cell name : WithBlankNamePrefix

   

   • library += WithBlankNamePrefix(name="N1", size=50): N1 will be the cell name with the class name as prefix.

     cell name : N1

   

   • library += WithBlankNamePrefix(size=60).with_name("N1"): N1 overwrite and used as the cell name.

     cell name : N1

   

   class WithBlankNamePrefix(fp.PCell):
       name: str = fp.NameParam(prefix="")
       size: float = fp.FloatParam()
   
       def build(self) -> Tuple[fp.InstanceSet, fp.ElementSet, fp.PortSet]:
           insts, elems, ports = super().build()
           TECH = get_technology()
           elems += fp.el.Rect(center=(0, 0), width=self.size, height=self.size, layer=TECH.LAYER.M2_DRW)
           return insts, elems, ports
   
   # gds cell name: WithBlankNamePrefix
   library += WithBlankNamePrefix(size=40)
   # gds cell name: N1, no prefix
   library += WithBlankNamePrefix(name="N1", size=50)
   # gds cell name: N1, force to use "N1" as cell name
   library += WithBlankNamePrefix(size=60).with_name("N1")`
   

3. Cell name with custom name prefix

   The third method is defining a name parameter fp.NameParam and setting the prefix to a custom name custom. This allow users to export the cell name without the class name prefix when using name parameter of the PCell (It overrides the name parameter in fp.PCell) and set the default cell name as they wish.

   • library += WithCustomNamePrefix(size=70): The cell name will be the name set in the name parameter.

     cell name : custom

   

   • llibrary += WithCustomNamePrefix(name="N1", size=80): N1 will be added after the cell name custom.

     cell name : custom_N1

   

   • library += WithCustomNamePrefix(size=90).with_name("N1"): N1 overwrite and used as the cell name.

     cell name : N1

   

   class WithCustomNamePrefix(fp.PCell):
       name: str = fp.NameParam(prefix="custom")
       size: float = fp.FloatParam()
   
       def build(self) -> Tuple[fp.InstanceSet, fp.ElementSet, fp.PortSet]:
           insts, elems, ports = super().build()
           TECH = get_technology()
           elems += fp.el.Rect(center=(0, 0), width=self.size, height=self.size, layer=TECH.LAYER.MT_DRW)
           return insts, elems, ports
   
   # gds cell name: custom
   library += WithCustomNamePrefix(size=70)
   # gds cell name: custom_N1
   library += WithCustomNamePrefix(name="N1", size=80)
   # gds cell name: N1
   library += WithCustomNamePrefix(size=90).with_name("N1")