Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

To delete a many-to-many (or many-to-one) mapping between components, follow these steps.

1.From the layout window Connectivity menu, choose Update – Device

Correspondence.

The layout window and the CIW prompt you to select one or more instances from the schematic window.

2.In the schematic, select one of the components in the group whose mapping you want to delete.

All the components in the group are highlighted.

3.Use Shift click to deselect all the components except one.

4.Press Return in the schematic window.

The layout window and the CIW prompt you to choose one or more instances from the layout window.

5.Use Shift click to deselect the components to be deleted except the one you want to map to the schematic component.

6.Press Return in the layout window.

The many-to-many (or many-to-one) mappings are deleted.

Using Virtuoso XL Properties

Before the Virtuoso XL layout editor can create a layout from a schematic, you must create a layout device for every symbol in the schematic. The layout master cell of a device or contact can be a fixed cell, aparameterized cell (pcell), or a device or contact defined in the technology file.

Pcells are often the most effective because you can assign the dimensions of the device at layout generation and vary the sizes of a contact each time you place the cell.

For more information about pcells, see the Virtuoso Parameterized Cell Reference Manual.

To tell Virtuoso XL which layout configuration of a schematic symbol to use in a design, you can

■Add the lxUseCell property to the symbols of device cells to specify which cell (or library and cell, if a you want to use a cell from different library) to use for the layout instance

Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

■Add or turn on the lvsIgnore, ignore, ignoreNames, or nlAction property on symbols in the schematic to keep them from being placed in the layout

■Add the lxIgnoredParams property to block unwanted parameters

■The lxRemoveDevice property ignores parasitic devices

■Add the lxViewList and lxStopList properties to the symbols of device cells in hierarchical designs to specify the layout views to use

Note: The lxIgnoredParams, lxViewList, and lxStopList properties have default values that are used when properties are not found. The corresponding environment variable names are lxIgnoredParams, viewList, and stopList. Their values are all strings containing words separated by spaces.

To use the Virtuoso XL layout editor to create complex devices and to generate your own internal net prefixes, you can

■Add the lxCombination is a user defined property used to build a complex set of devices, which is comprised of series (sfactor) and parallel (mfactor) connections.

Note: The lxCombination property supports a maximum of two terminal devices.

■Add the lxNetNamePrefi property to add a prefix to internal nets in the layout

Using the lxUseCell Property to Specify Layout Devices to Use

When a device symbol has more than one layout cell associated with it, you can tell Virtuoso XL which cell to use in generating the layout by setting the lxUseCell property for the symbol as one of the following:

■A property of the symbol instance in the schematic

■A property of the symbol master in the library

■A component description format (CDF) parameter of the symbol

Note: The CDF default parameters are not passed to the layout instance that has a lxUseCell property defined. If you require the CDF parameters to be passed to the layout instance that has the lxUseCell property defined, then the schematic CDF parameters should have the storeDefault option set to yes.

Virtuoso XL looks for the lxUseCell property in the order listed above.

For digital designs, the cells can be in different libraries.

Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

For mixed-signal designs, you must use a CDF to define the parameters for the devices; therefore, the symbol and layout must be in the same library and cell.

If a symbol does not have an lxUseCell property or the property is not assigned a value,

Virtuoso XL defaults to the cell with the same library and cell name as the symbol.

If there is already an instance of the cell with the expected name in the layout, the software uses that instance.

Specifying the Layout Device in the Symbol Instance

To specify a layout device in the symbol instance, set the lxUseCell property on a symbol instance in the schematic. To set a property on a symbol instance, follow these steps.

1.From the schematic window, choose Design – Make Editable to make the design editable.

2.In the schematic window, click on the symbol to select it.

3.From the schematic window, choose Edit – Properties – Objects.

Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

The Edit Object Properties form appears.

4. Click Add.

Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

The Add Property form appears.

5.Type lxUseCell in the Name field.

6.Set the Type cyclic field tostring.

7.Type the name of the layout device to use in the Value field.

8.Click OK.

Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

The lxUseCell property appears in the Edit Object Properties form.

9.Click OK.

Virtuoso XL uses the cell you specified when you generate or reinitialize the layout.

Specifying the Layout Device in the Symbol Master

To specify the layout device in the symbol master, set the lxUseCell property on a symbol master in the schematic.

To set a property on a symbol master in the schematic, follow these steps:

1. Open the symbol master of the device.

Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

2.From the schematic window, choose Edit – Properties – Cellview.

The Edit Cellview Properties form appears.

3.In the Property section of the form, click Add. (If the Add option is not visible, click user at the top of the form.)

The Add Property form appears.

4. Type lxUseCell in the Name field.

Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

5.Set the Type cyclic field tostring.

6.Type the layout device name in the Value field.

7.Click OK.

The lxUseCell property appears in the Edit Cellview Properties form.

8.Click OK.

Virtuoso XL uses the layout device you specified for the symbol when you generate or reinitialize the layout.

Specifying the Layout Device in the Device Component Description Format

To specify the layout device in the device CDF, you add the lxUseCell default parameter to the device CDF.

To add a default parameter to the device CDF, follow these steps.

1. In the Command Interpreter Window (CIW), choose Tools – CDF – Edit.

Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

The Edit Component CDF form appears.

2.In the Library Name field, type the library name.

3.In the Cell Name field, type the cell name.

Note: Do not click OK or Apply or press Enter: these actions cause the form to disappear.

Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

The Edit Component CDF form expands to include information about the device.

lib1

4. Click Add.

Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

The Add CDF Parameter form appears.

defValue field

5.Set the paramType cyclic field tostring.

6.In the name field, typelxUseCell.

7.In the defValue field, type the name of the layout device you want to use.

8.Click OK.