Product Documentation
Virtuoso Space-based Router Command Reference
Product Version IC23.1, September 2023

connect_fill

connect_fill
[ -nets {s_netName…} | -set d_setObj ]
[ -layer {s_layerName …} ] 
[ -all | -region {f_xlo f_ylo f_xhi f_yhi} ] 
[ -mode {mesh | tree} ] 
[ -keep_simple_connections [ true | false ] ] 
[ -lock_via_layers {s_layerName …} ] 
[ -threads i_threads ]

Description

Connects fill shapes to the specified power and/or ground nets.

Arguments

-all

Processes the entire design. This is the default.

-keep_simple_connections [ true | false ]

If false, which is the default, connections to fill shapes that do not participate in reducing the IR drop are excluded. This argument only applies to the mesh connection mode.

-layer {s_layerName…}

Specifies the layers to process. By default, all routing layers are processed.

-lock_via_layers {s_layerName…}

Prevents this command from adding vias on the specified cut layers. By default, all via layers can be used.

-mode {mesh | tree}

Chooses the connection method.

mesh

(Default) Connects fill shapes to the specified power/ground nets using the maximum number of vias possible. Fill shapes can carry current as part of the power and ground structure. Increasing the number of cuts helps to reduce IR drop.

tree

Connects fill shapes to the specified power/ground nets using the minimum number of vias possible given by the minNumCut rule.

-nets {s_netName…}

Connect added fill shapes to the given nets. The power/ground nets must be listed in the SPECIALNETS section of the DEF file. If several nets are given, connections to the nets are made in the order they are given in the list. If neither -nets nor -set is given, Space-based Router and Chip Optimizer attempts to connect to all power and ground nets.

-region {f_xlo f_ylo f_xhi f_yhi}

Specifies the boundary of the area to process, given the lower left and upper right coordinates.

-set d_setObj

Connects fill shapes to nets in the set. Specified power/ground nets must be listed in the SPECIALNETS section of the DEF file. There is no control on the net priorities to connect the fill shapes. If neither -nets nor -set is given, Space-based Router and Chip Optimizer attempts to connect to all power and ground nets.

-threads i_threads

Specifies the number of threads or processors to use in parallel to run this command. By default, if multi-threading has been enabled (enable_multithreading), the session threads are used, otherwise, one processor is used.

Examples

Mesh Connection Mode Without Keeping Simple Connections (Default)

The following figure shows vias added to connect fill shapes to power (VDD) and ground (VSS) nets in mesh mode using the following command:

connect_fill -mode mesh -nets {VSS VDD}

In the example, only connections which improve the IR drop are included.

Mesh Connection Mode Keeping Simple Connections

The following figure shows vias added to connect fill shapes to power (VDD) and ground (VSS) nets in mesh mode using the following command:

connect_fill -mode mesh -nets {VSS VDD} -keep_simple_connections

The connections in this example are the same as the previous mesh mode example, with the exception that the Metal2 shape in the center of the figure is connected to VDD. The vias for this shape represent a simple connection that does not affect the IR drop.

Tree Connection Mode

The following figure shows vias added to connect fill shapes to power (VDD) and ground (VSS) nets in tree mode using the following command:

connect_fill -mode tree -nets {VSS VDD}

While mesh mode tries to maximize connections, tree mode attempts to make connections with the minimum number of cuts required.

Related Topics

Optimize Commands

create_fill

delete_fill


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