Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

If Virtuoso XL needs to create a group, the group is called lxMTM. A property called lxMTM is created and attached to the group in the layout. The property value is the name of all the selected components from the schematic. All the components selected from the layout are the members of the group.

Note: More than one group in a layout cellview can be named lxMTM. But a component can belong to only one such group.

You can repeat this process to assign all the elements in the “many” group to nets.

5. Press Escape to cancel the Device Correspondence command.

Using Many-to-Many or Many-to-One Mapping

You can map multiple devices in the schematic to one or more devices (including shapes) in the layout by using the Update Components and Nets command. You might want to do this if you need to map a symbol or symbols in the schematic to a flattened layout instance.

Note: You can map many-to-many devices only between cellview pairs; that is, between the schematic and layout that correspond to each other and are on the same hierarchical level.

For example, you cannot map an instance in the one to multiple instances accessed through a descend edit in the other.

To map multiple symbols in the schematic to one or more instances in the layout, follow these steps.

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

The schematic window and the Command Interpreter Window (CIW) prompt you to choose one or more instances from the schematic.

2.Select the components to be mapped from the schematic.

3.Press Return in the schematic window.

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

You can select more than one device by Shift click or by click and drag. You can deselect using Control click or by Control click and drag. Preselected components are considered part of the selection unless you specifically deselect them.

For example, in the diagram below, you could select the resistors R1and R2, NMOS transistors N1 and N2, and devices X and Y from the schematic to be mapped to the devices L and M in the layout (many-to-many) or the block MISC in the layout (many-to- one).

Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

The number of external nets in the selected group in the schematic (in the example, Nets

A, B, and C) must be the same as the number of external nets in the selected group in the layout.

The software lets you ignore global nets, such as Vdd and Gnd, in the schematic because global nets are not indicated on many schematics. But if a schematic has global nets, they must be shown in the layout.

4.When you have finished your selection, pressReturn in the layout window.

If you are assigning many-to-many, the Device Correspondence command checks to see that the layout components are all in one group.

If they are all in the same group, Virtuoso XL leaves them in the group and the CIW displays a message that mapping has been successful.

If only some of them are in a group, Virtuoso XL puts the rest in the group and the CIW displays a message that mapping has been successful.

If none of them is in a group, Virtuoso XL creates a new group and puts them all in. The CIW displays a message that mapping has been successful.

If they are in different groups, the CIW displays a message that mapping cannot be set because they are in different groups.

If Virtuoso XL needs to create a group, the group is called lxMTM. A property called lxMTM is created and attached to the group in the layout. The property value is the name

Virtuoso XL Layout Editor User Guide

Preparing Your Connectivity Source for the Virtuoso XL Layout Editor

of all the selected components from the schematic. All the components selected from the layout are the members of the group.

Note: More than one group in a layout cellview can be named lxMTM. But a component can belong to only one such group.

After the components are checked, the Device Correspondence command creates the new group.

Modifying Many-to-Many or Many-to-One Mapping Between Components

To modify a 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 that you want to modify. All the components in the group are highlighted.

3.To delete some schematic components from or add others to the group, use Control click to select those components to add and Shift click to deselect the components to be deleted.

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.To delete some layout components from or add others to the group, use Control click to select those components to add and Shift click to deselect the components to be deleted.

6.Press Return in the layout window.

The new mapping is checked and, if found acceptable, created.

Deleting Many-to-Many or Many-to-One Mapping Between Components

To delete a mapping between components, use the Update – Device Correspondence command to set a one-to-one mapping between the components.