Virtuoso XL Layout Editor User Guide

Editing Your Layout with Virtuoso XL Layout Editor

5.If you do not want the fingers that are created to be chained (abutted in a stack), turn off

Chain Fingers.

6.Click Apply.

7.Move the cursor into the layout window.

A representation of the fingers of the transistor follows the cursor in the layout window.

8.Click in the layout where you want to place the transistor fingers. The transistor fingers are placed where you click.

If you have selected more than one transistor, you can press the Next or Previous buttons to move to another transistor. You must click Apply to save the changes to a transistor before clicking Next or Previous.

Note: When the Fold Transistors command is active, you cannot select any pcell that has a fingering value set to greater than 1.

Note: If you enter an lxMaxWidth parameter that would yield a device with more than 999 fingers (for example, a device width of 2 andlxMaxWidth of1 , which could result in a device folded in 2 M fingers), the Command Interpreter Window (CIW) prints a warning and does not fold the device. You can still fold such a large device manually.

Adding Instances to a Layout

To add an instance not present in the schematic to the layout, you can add the instance to the schematic and connect it to a net, as explained below, or you can add it to the layout using the layout editor Create Instance command and connect it with the Virtuoso XL Update Components and Nets command.

Note: The schematic must be opened in edit mode.

To add an instance not present in the schematic to the layout, follow these steps.

1. In the schematic window, choose Add – Instance.

Virtuoso XL Layout Editor User Guide

Editing Your Layout with Virtuoso XL Layout Editor

The Add Instance form appears.

2.In the Library field, type the library name of the new instance.

3.In the Cell field, type the cell name of the new instance.

4.In the View field, type the view name of the new instance.

5.In the Names field, type the instance names (if any).

6.Move the cursor to the schematic.

The outline of the instance follows the cursor.

7.Click in the schematic where you want to place the instance. The instance is placed in the schematic.

8.To connect the instance to a net, use the schematic window Add – Wire command.

9.When you have finished adding instances to the schematic, from the layout window, choose Connectivity – Update – Components and Nets.

A dialog box asks whether you want to extract the schematic.

10.Click Yes.

Virtuoso XL extracts the schematic and adds the instance to the layout.

Virtuoso XL Layout Editor User Guide

Editing Your Layout with Virtuoso XL Layout Editor

Note: If you have a large design and are only adding a few instances, it saves time to use the

Connectivity – Update – Device Correspondence to update each instance rather than using Connectivity – Update – Components and Nets to update the whole design.

Note: If the instance does not need to be connected to a net, add it directly to the layout and add the lvsIgnore property to it.

Adding Pins to a Layout

Pins occurring in both the schematic and the layout must have identical names. If you add pins that are not in the schematic to the layout, Virtuoso XL maintains their connectivity in the layout. To add a pin to the layout, follow these steps.

1.In the Layer Selection Window (LSW), choose the layer on which you want to create the pin.

2.From the layout window, choose Create – Pin.

Virtuoso XL Layout Editor User Guide

Editing Your Layout with Virtuoso XL Layout Editor

The Create Symbolic Pin form appears.

3.In the Terminal Names field, type the terminal name for the pin.

The pin name must match the name of an existing net in the schematic. You can create more than one pin with the same name.

4.In the I/O Type section, choose the appropriate I/O type.

Note: To create a pin for a net that is not on the schematic (a feedthrough, for example), give the pin a new name.

5.In the layout window, click to place one corner of the pin; then click to place the opposite corner of the pin.

The pin appears on the layout window.

Note: Do not place pins where you do not want to make a connection. For example, do not create a pin on poly that covers the gate area of a FET.