Hi, I have a mixed-signal design with two separate ground (AGND and DGND) and power supplies (AVDD and DVDD). I imported them into Magic, without connecting them to each other. When I extract the Spice file, Magic changes all the DGND into AGND. However, when I extract the Spice file separately, everything is correct. Do you know why it happens? Thanks.

@sepide asgari This is probably happening because the grounds connect through the pwell substrate. If they need to be totally separated, you can place one region in a dnwell surrounded by an nwell guard ring. If you don’t mind the connection through the pwell substrate, to pass LVS, enclose one region in

81/53

This is

areaId.substrateCut

in klayout and

isosubstrate

in magic.

Thank you for your help. When I separate the blocks by dnwell, Magic can export both DGND and AGND. Would you please tell me how I can use isosubstrate in Magic? What is the command? Thanks.

Just paint on the

isosubstrate

layer.