create_pg_fill

create_pg_fill 
[ -set d_setObj | -nets {s_netName…} ] 
[ -all | -region {f_xlo f_ylo f_xhi f_yhi} ] 
[ -layer {s_layerName…} ] 
[ -lock_via_layers {s_layerName …} ] 
[ -connections [ true | false ] ] 
[ -connections_type [all | via | same_layer] ] 
[ -keep_simple_connections [ true | false ] ] 
[ -silent | -verbose ] 
[ -threads i_threads ] 

Description

Creates fill shapes connected to power and ground nets to improve IR drop while also increasing metal density. This command performs the following:

• Inserts the maximum number of stripes as possible in the preferred routing direction on each given layer, respecting all the existing power/ground spacing and width constraints:
  • pgFillWidth is the width of the power/ground fill stripes to insert. A small width is recommended to minimize the impact on the timing. If pgFillWidth is not defined, two times minWidth is used.
  • minPgFillSpacing is the minimum spacing between two power/ground fill stripes. If minPgFillSpacing is not defined, the first defined value is used from the following: minSameNetSpacing*2 or minSpacing*2.
  • minPgFillSignalSpacing is the minimum spacing between power/ground fill stripes and signal nets. If minPgFillSignalSpacing is not defined, two times minSpacing is used.
  • minPgFillClockSpacing is the minimum spacing between power/ground fill stripes and clock nets. If minPgFillClockSpacing is not defined, minPgFillSignalSpacing is used.
  • minPgFillPgSpacing is the minimum spacing between power/ground fill stripes and existing power/ground nets. If minPgFillPgSpacing is not defined, minPGFillSignalSpacing is used.
  • minPgFillFloatingFillSpacing is the minimum spacing between power/ground fill stripes and existing floating fill shapes. If minPgFillFloatingFillSpacing is not set, then minPgFillSpacing is used.
  • minPgFillBoundarySpacing is the minimum spacing between power/ground fill stripes and the design boundary. If minPgFillBoundarySpacing is not defined, then minBoundaryInteriorHalo is used, and if neither is defined, then the default is 0.
• Connects all stripes to the given power/ground nets (-nets or -set).
• Removes all fill shapes with less than two connections because these shapes will not help to improve the IR drop (-connections true -keep_simple_connections false).

The create_pg_fill command does not consider metal density requirements. Following this command, run check_density to verify the metal density, and create_fill to add additional fill shapes as needed.

Arguments

-all	Processes the entire design. This is the default.
-connections [ true | false ]
	(Default) If true, connects the created fill stripes to the nets specified by -nets or -set, and all remaining floating fill stripes are removed. If false, creates as many floating fill stripes as possible.
-connections_type [all | via | same_layer]
	Specifies how power/ground fill shapes can be connected to power/ground rails.
	all	Both via and same-layer connections are used. This is the default.
	same_layer	Connects fill stripes directly to same-layer power rails.
	via	Uses vias to connect fill stripes to power rails.
-keep_simple_connections [ true | false ] ]
	(Applies only with -connections true) If false, removes fill stripes that do not help to improve IR drop (stripes that are floating/unconnected or with fewer than two connections). Default: false
-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.
-nets {s_netName…}	Connect added fill stripes to the given nets. Specified power/ground nets must be listed in the SPECIALNETS section of the DEF file. If several nets are given, Space-based Router and Chip Optimizer attempts to connect to the nets 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 stripes 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 stripes. If neither -nets nor -set is given, Space-based Router and Chip Optimizer attempts to connect to all power and ground nets.
-silent	Outputs only essential messages.
-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.
-verbose	Outputs additional messages.

Examples

The following commands set power/ground fill constraints for layer M3.

set_layer_constraint -constraint pgFillWidth -layer M3 -Value 0.1
set_layer_constraint -constraint minPgFillSpacing -layer M3 -Value 0.2
set_layer_constraint -constraint minPgFillSignalSpacing -layer M3 -Value 0.3
set_layer_constraint -constraint minPgFillClockSpacing -layer M3 -Value 0.6
set_layer_constraint -constraint minPgFillPgSpacing -layer M3 -Value 0.4
set_layer_constraint -constraint minPgFillBoundarySpacing -layer M3 -Value 0.5

The following figure shows fill stripes added to an area and the power-to-fill and fill-to-fill connections. Some fill stripes are interrupted by existing signal wires that are outlined in black. By default and when -connections is set true, the added fill stripes with only one connection to the power net will be removed as indicated in the figure. This example uses via connections only (-connections_type via).

Related Topics

Optimize Commands

create_fill

delete_fill

Return to top