HINTS & TIPS

Q: I took the example file mux4.gds from Expert's installation and tried the Edit-in-place operation. I entered into an instance of mux1, modified a box in it and exited from EIP. There are options to change the edited cell and to save instance under another cell name. I selected the latter option, but all four instances of mux1 in mux4 have been changed, rather than the instance I modified in place.
(see Figure 1)

Figure 1. Mux4.gds during and after editing in place.

 

A: This behavior is not a bug. As you may have noticed, cell mux4 contains a 1x4 array of cell mux1. When you edit in place an element of an array, you are editing all elements of the array. If you change a single instance from this array, the whole array will be destroyed. You must split the array into separate instances or rows or columns first. See Figure 2.

Figure 2. Instance/array modification dialog.

 

Q: What is the difference between "flat" and "hierarchical" modes in the DRC script panel of Expert?

A: Flat vs. hierarchical are modes for error reports only. Expert runs DRC checks in flat mode, but it groups errors into cells where they actually occur. For example, if you have 15000 instances of a via cell with contact of the wrong size, flat mode will report 15000 errors, while hierarchical mode will report only one. Clearly, this is a great convenience when you need to analyze DRC error reports. The actual checks are performed in exactly the same way for both modes. A truly hierarchical DRC checker, Dragon is expected soon from Silvaco.

Q: When drawing boxes Expert provides a prompt in the message line about box parameters. We have noticed that sometimes that information goes away, for example, when a box is moved. Also, if a box gets converted to a polygon, the information is no longer available.

 

A: Information in the message line is "volatile": It is always updated for the current operation. If you want to see info about an object again, select it or pick it for modification.

Q: How can I view a set of coords with either the window view or pan view?...Basically I'm hunting drc errors down by coordinates and haven't found the easiest way to do this.

 

A: There are "Cursor Position" fields in Expert just above the layout window. There is also a field to select the measurement units. You can enter the required coordinates in the Cursor "Position" fields and then press the <Enter> key. The cursor will go to the required point. If this point was off screen, Expert will pan to this point. If the cursor is in the layout window, then you may press <Ctrl-P> to start the input of cursor position.