Routing Constraint Manager User Interface

Use the Routing Constraint Manager to create, modify, and delete routing constraints. The Routing Constraint Manager has the following components:

Routing Constraint Manager Toolbar	Lets you create, save, and delete constraints. It also provides access to a number of constraint types (Group, Bus, Symmetry, DiffPair, Match) and allows you to specify your constraint configuration.
Routing Constraint Manager Summary Information	Displays the summary information of the nets in the Routing Constraint Manager.
Routing Constraint Manager Tabs	Lets you edit the routing constraints. In Routing Constraint Manager, there are eight tabs. These tabs include a number of options to set specific constraints. The supported routing constraints in Virtuoso are: Shielding, Diff Pair, Bus, Matched Length, Symmetry, Process Rule Overrides, Net Class.

Routing Constraint Manager Toolbar

The following table lists the functions of the different buttons on the Routing Constraint Manager toolbar:

Icon	Command	Description
	Load Constraints	Loads constraint options from an existing file.
	Save Table Contents	Saves the contents of the table for a given constraint in the csv or xml format.
	Edit Design Process Rule Overrides	Lets you edit the user-defined design default constraint group.
	NetClass	Creates a group (NetClass) constraint for all the selected nets.
	Bus	Creates a bus constraint for the selected nets.
	Symmetry	Creates a symmetry constraint for the selected nets.
	DiffPair	Creates a differential pair constraint for the selected nets.
	Match	Creates a matched length constraint for the selected nets.
	Apply Constraint Group	Applies a constraint group to the selected nets or groups.
	Apply Shield Constraint Group	Applies a parallel simple shielding constraint group to the selected nets or groups.
	Apply Max Resistance	Creates a maximum resistance constraint on a net.
	Routing Results	Displays the Routing Results Browser window.
	Remove	Deletes the constraint applied on the selected nets or groups.
	Show Constrained Nets	Displays only the constrained nets.
	Show Unconstrained Nets ON	Displays only the unconstrained nets.
	Show Signal Nets	Displays only the signal nets.
	Show Supply Nets	Displays only the power and ground nets.
	Snapshot Selected	Displays only the nets that are selected in the Navigator assistant.
	Synchronize Snapshot	Synchronizes the net selection in Routing Constraint Manager with the ones that are currently selected in the Navigator assistant or layout canvas This sync option works in conjunction with the Snapshot Selected option. Once you have created a snapshot of the selected nets, the Synchronize Snapshot button updates the snapshot to match the nets that are selected in the Navigator assistant or layout canvas.
	Select All	Selects all the nets in the table.
	Deselect All	Deselects all the nets in the table.
	Undo	Reverses the action of the previous constraint editing operation. The bindkey associated with this is `Ctrl + X`.
	Redo	Reapplies a constraint editing operation that was reversed by an undo command. The bindkey associated with this is `Ctrl + Shit + Z`.
	Refresh Table	Refreshes the constraints table.
	Check Constraints	Checks whether the specified constraints have been implemented correctly in the layout.
	Column Visibility Presets	Loads existing presets. This lets you decide which columns are relevant to be displayed
	Save Column Visibility Preset	Lets you create and save a column visibility preset.
	Delete Column Visibility Preset	Lets you delete a column visibility preset.

Routing Constraint Manager Summary Information

The following table lists the net summary information in Routing Constraint Manager:

Label	Description
Signals	Shows the number of signal nets.
Supplies	Shows the number of power and ground nets.
Constrained	Shows the number of constrained nets.
Unconstrained	Shows the number of unconstrained nets.
Selected	Shows the number of selected nets.

Routing Constraint Manager Tabs

The following table lists the functions of the different tabs in the Routing Constraint Manager:

Tab	Description
Nets	Provides an overview of the constraints applied on each net, including groupings of nets.
Process Rule Overrides	Displays all the constraint groups in the design. Each group can be expanded to see which nets the constraint groups are applied to.
NetClass	Displays different types of net groups.
Bus	Displays the bus groups in the design and their net constraints.
Match	Displays the match length groups in the design and their net constraints.
DiffPair	Displays the diffpair groups in the design and their net constraints.
Symmetry	Displays the symmetry groups in the design and their net constraints.
Shield	Displays all shield constraint groups. Each group expands to display which nets the shield applies to.
Max Resistance	Defines the maximum resistance permissible between two terminals or instance terminals or, between a terminal or instance terminal and all the terminals or instance terminals connected to it.

Nets

The following table describes the columns available in the table in the Nets tab of the Routing Constraint Manager.

Column	Description
Net	Name of the net.
Pin Count	Number of pins for each net.
Priority	Priority of the constraint applied to a net.
Net Process Rule Overrides	Rules that are applied to a net.
Group Process Rule Overrides	Rules that are currently applied to a net group. The two columns Net Process Rule Overrides and Group Process Rule Overrides behave identically to the existing Process Rule Overrides column. Previously, constraint groups applied to groups could only be seen by opening a group editor.
NetClass	Group constraint applied to a net.
Bus	Bus constraint applied to a net.
Symmetry	Symmetry constraint applied to a net.
DiffPair	Diffpair constraint applied to a net.
Match	Match constraint applied to a net.
Shield	Shield constraint applied to a net or a group of nets.
Shield Net 1	Name of the first net that is to be considered as the shield net. This shield net behaves identically to the original Shield column.
Shield Net 2	Name of the second net that is to be considered as the shield net. This shield net behaves identically to the original Shield column.
Via Config	Via configuration constraint group applied to a net or a group. The full functionality will be available in a future release.
Max Resistance	Maximum resistance constraint applied to a net.

Process Rule Overrides

The following table describes the columns available in the table in the Process Rule Overrides tab of the Routing Constraint Manager.

Column	Description
Process Rule Overrides	The constraint group applied to a net or a group of nets.
Via Config	The via configuration constraint group applied to a net or a group of nets. The full functionality will be available in a future release.
Dir	The preferred routing direction for the layer.
Vias	A valid vias constraint.
Cuts	The minimum number of cuts constraint (for each cut layer matching a valid via).
Bottom Layer	The name of the valid bottom routing layer.
Top Layer	The name of the valid top routing layer.
<Metal Layer> W Min	The minimum width of the metal layer.
<Metal Layer> W Max	The maximum width of the metal layer.
<Metal Layer > S	The minimum spacing of the metal layer.

NetClass

The following table describes the columns available in the table in the NetClass tab of the Routing Constraint Manager.

Column	Description
NetClass	The name of the constraint group applied to the nets.
Process Rule Overrides	The constraint group applied to a net or a group of nets.
Same Mask	Displays the mask name for the NetClass constraint.
Shield	The name of the shield constraint group applied to the group of nets (if one has been applied).
Via Config	The via configuration constraint group applied to a net or a group of nets. The full functionality will be available in a future release.
Dir	The preferred routing direction of the layer.
Vias	A valid vias constraint.
Cuts	The minimum number of cuts constraint (for each cut layer matching a valid via).
Bottom Layer	The name of the valid bottom routing layer.
Top Layer	The name of the valid top routing layer.
<Metal Layer> W Min	The minimum width of the metal layer.
<Metal Layer> W Max	The maximum width of the metal layer.
<Metal Layer S >	The minimum spacing of the metal layer.

Bus

The following table describes the columns available in the table in the Bus tab of the Routing Constraint Manager.

Column	Description
Bus	The name of the bus constraint applied to a net or a group of nets.
Process Rule Overrides	The constraint group applied to a net or a group of nets.
Shield	The name of the shield constraint group applied to the group of nets (if one has been applied).
Via Config	The via configuration constraint group applied to a net or a group. The full functionality will be available in a future release.
Dir	The preferred routing direction of the layer.
Vias	A valid vias constraint.
Cuts	The minimum number of cuts constraint (for each cut layer matching a valid via).
Bottom Layer	The name of the valid bottom routing layer.
Top Layer	The name of the valid top routing layer.
<Metal Layer> W Min	The minimum width of the metal layer.
<Metal Layer> W Max	The maximum width of the metal layer.
<Metal Layer S >	The minimum spacing of the metal layer.

Match

The following table describes the columns available in the table in the Match tab of the Routing Constraint Manager.

Column	Description
Match	The name of the matched length constraint applied to a net or a group of nets.
Process Rule Overrides	The constraint group applied to a net or a group of nets.
Pattern	The pattern used to lengthen wires for matched length routing. The different patterns are: None, Accordion, RW Accordion, Trombone, and End Run.
Match Per Layer	Length match checks performed per layer or over the entire length of the net.
Tolerance%	Absolute tolerance when matching net lengths is expressed as a percentage of the total length.
Shield	The name of the shield constraint group applied to the group of nets (if one has been applied).
Via Config	The via configuration constraint group applied to a net or a group of nets. The full functionality will be available in a future release.
Dir	The preferred routing direction of the layer.
Vias	A valid vias constraint.
Cuts	The minimum number of cuts constraint (for each cut layer matching a valid via).
Bottom Layer	The name of the valid bottom routing layer.
Top Layer	The name of the valid top routing layer.
<Metal Layer> W Min	The minimum width of the metal layer.
<Metal Layer> W Max	The maximum width of the metal layer.
<Metal Layer S >	The minimum spacing of the metal layer.

DiffPair

The following table describes the columns available in the table in the DiffPair tab of the Routing Constraint Manager.

Column	Description
DiffPair	The name of the differential pair constraint applied to a net or a group of nets.
Process Rule Overrides	The constraint group applied to a net or a group of nets.
Tolerance	Specifies the absolute tolerance when matching differential pair for violation detection.
Same Mask	Displays the mask name for the DiffPair constraint.
Shield	The name of the shield constraint group applied to the group of nets (if one has been applied).
Via Config	The via configuration constraint group applied to a net or a group of nets. The full functionality will be available in a future release.
Dir	The preferred routing direction for the layer.
Vias	A valid vias constraint.
Cuts	The minimum number of cuts constraint (for each cut layer matching a valid via).
Bottom Layer	The name of the valid bottom routing layer.
Top Layer	The name of the valid top routing layer.
<Metal Layer> W Min	The minimum width of the metal layer.
<Metal Layer> W Max	The maximum width of the metal layer.
<Metal Layer S >	The minimum spacing of the metal layer.

Symmetry

The following table describes the columns available in the table in the Symmetry tab of the Routing Constraint Manager.

Column	Description
Symmetry	The name of the symmetry constraint applied to a net or a group of nets.
Process Rule Overrides	The constraint group applied to a net or a group of nets.
Tolerance	Specifies the absolute tolerance when matching symmetries for violation detection.
Axis	The axis to be used for symmetry. The axis symmetry can be vertical and horizontal.
Same Mask	Displays the mask name for the symmetry constraint.
Shield	The name of the shield constraint group applied to the group of nets (if one has been applied).
Via Config	The via configuration constraint group applied to a net or a group of nets. The full functionality will be available in a future release.
Dir	The preferred routing direction for the layer.
Vias	A valid vias constraint.
Cuts	The minimum number of cuts constraint (for each cut layer matching a valid via).
Bottom Layer	The name of the valid routing bottom layer.
Top Layer	The name of the valid routing top layer.
<Metal Layer> W Min	The minimum width of the metal layer.
<Metal Layer> W Max	The maximum width of the metal layer.
<Metal Layer S >	The minimum spacing of the metal layer.

Shield

The following table describes the columns available in the table in the Shield tab of the Routing Constraint Manager.

Column	Description
Shield	The name of the shielding constraint group applied to a net or a group of nets.
Shield Type	Determines the type of shielding to route around a net. The available options are: None: No shield. Parallel: Planar shield wires parallel to the signal wire. Tandem: Shield wires on a given layer above and below the signal wire. Coaxial: Both tandem and parallel shields to surround the signal wire on all four sides The default value is Parallel.
Group Shield Type	Displays the type of group shielding.
Enclosure Style	Adds shield wires all around the vias in the preferred direction.
Tolerance%	Absolute tolerance when matching shield lengths is expressed as a percentage of total coverage.
Valid Shield Layers	List of layers that are valid for the shielding routing.
Share Shields	Determines whether shield routes can be shared by nets.
Use Existing Shapes	Determines whether existing shapes can be used as shielding.
Shield Terminal	Determines whether shield terminal has to be connected or not.
Minimum Length Enabled	Prevents shielding of any signal wire that is shorter than the given length. If selected, it enables the Minimum Length column.
Minimum Length	Specifies a minimum value for which shielding wires are added.
Tie Shield	Determines whether ties should be added to tie the new shield wires to the shield nets that they belong to.
Tie Frequency Enabled	Displays whether the tie frequency is enabled.
Tie Frequency	Specifies the maximum distance between ties that must be inserted to tie the new shield wires to their respective shield nets.
Shield Redundant Via	Adds redundant vias to tie shield wires to shield nets at every location where the shield wires overlap their respective existing power or ground rails.
Via Config	The via configuration constraint group applied to a net or a group. The full functionality will be available in a future release.
Dir	The preferred routing direction of the layer.
Vias	Corresponds to a valid vias constraint.
Cuts	The minimum number of cuts constraints (for each cut layer matching a valid via).
Bottom Layer	The name of the valid routing bottom layer.
Top Layer	The name of the valid routing top layer.
<Metal Layer> W Min	The minimum width of the metal layer.
<Metal Layer> S	The minimum spacing of the metal layer.

Max Resistance

The following table describes the columns available in the table in the Max Resistance tab of the Routing Constraint Manager.

Column	Description
Net	The net name on which the maximum resistance constraint is defined.
To Inst Term	The from-to terminals of the net on which the maximum resistance constraint should apply.
Max Resistance	The value of the maximum resistance.

Routing Constraint Manager Context-Sensitive Menus

The context-sensitive menus in the Routing Constraint Manager are displayed when you right-click a net or a constraint that appears on a net. These menus have options that are dependent on the Routing Constraint Manager tab, column, and the item selected. The options on the context-sensitive menus can include creating a new constraint, adding to an existing constraint, removing from a constraint, or deleting an existing constraint depending on the item selected. The create new or add options appear in the net, group, rules, and shield columns. The delete and remove options appear if an existing group or a constraint group is selected.

Virtuoso Automated Chip Assembly Routing Flow Guide
Product Version IC23.1, October 2023