check_length

check_length
[ -do_composite [ true | false ] ] 
[ -file s_fileName ] 
[ -match_paths [ true | false ] ] 
[ -min_segment_length f_micron ] 
[ -report ] 
[ -set d_setObj ] 
[ -sink_driver [ true | false ] ] 

Description

Reports length violations based on the settings of the following constraints:

• routeMinLength
  When this constraint is set, errors are reported on nets with routes that are shorter than routeMinLength.
• matchTolerance
  (Applies only for net groups of type net_match) Errors are reported on nets that are shorter than the longest net of the group minus the matchTolerance. Lengths are based on the net’s routes. If both matchTolerance and msTolerance are set, matchTolerance is used. However, for interoperability, you should only use msTolerance, not matchTolerance. The default setting is two times the pitch or four times the gap space is used for the tolerance.
• msMatchPerLayer
  For net groups of type net_match, when this constraint is set to true, length checks are performed by layer.
• msTolerance
  (Applies only for net groups of type net_match) Errors are reported on nets that are shorter than the longest net of the group minus the msTolerance percentage. Lengths are based on the net’s routes. If both matchTolerance and msTolerance are set, msTolerance is ignored. However, for interoperability, you should only use msTolerance, not matchTolerance. The default setting is two times the pitch or four times the gap space is used for the tolerance.
  For example, if msTolerance is 10, or 10%, and the longest net is 20 microns, then a net length of 18.2 microns would be acceptable because it is greater than the longest net minus 10% of 20 (2 microns). A net length less than 18 microns would fail.

The following information is given in the report:

Group	Name of the net’s net group
Net	Name of the net
Layer	Name of the layer (msMatchPerLayer checks only)
Delta	Difference between net’s route length and either the routeMinLength (if set), or the route length of the longest net of the group (Constraint-Length)
Length	The net’s route length
Constraint	routeMinLength (if set), or the route length of the longest net of the group
Tolerance	Absolute tolerance from matchTolerance (if set) or msTolerance (if set and matchTolerance is not set), otherwise two times the routing pitch or four times the gap space is used

Nets must be detail routed before using this command.

Arguments

-do_composite [ true | false ]
	If set to true, checking is performed at the composite level for net pair groups. Default: false
-file s_fileName	Outputs results to the named file.
-match_paths [ true | false ]
	When true, will report errors on route paths of the same net between terminals. Default: false
-min_segment_length f_micron
	Only checks segments that are longer than this length.
-report	Reports on all nets that are evaluated. By default, only violating nets are reported.
-set d_setObj	Specifies the set of nets or composite nets to operate on. By default and when this argument is not given, all nets in the design will be processed.
-sink_driver [ true | false ]
	When true, will report errors on routes of the same net between sink-driver terminals. Default: false

Examples

The following example creates a net group of all nets whose names start with MATCHB, then detail routes the nets and checks the lengths of the nets against each other.

update_net_connectivity -all
set MATCHBset [find_net -name MATCHB*]
create_group -name MATCHB -set $MATCHBset -type net_match 

# create a constraint group for the net_match group and initialize the new
# constraint group with the constraints from the LEFDefaultRouteSpec
create_constraint_group -name GM -type group2group
set_constraint_group -default GM -net_group MATCHB
copy_constraint -group LEFDefaultRouteSpec -to_group GM

# route the nets
detail_route

# check lengths
check_length -set $MATCHBset

The following example shows reported errors:

LENGTH ERROR: Group MATCHB Net MATCHB1 Delta 33.00 Length 39.50 Constraint 72.50
Tolerance 2.40
LENGTH ERROR: Group MATCHB Net MATCHB0 Delta 7.10 Length 65.40 Constraint 72.50
Tolerance 2.40
CHECK LENGTH: 2 Errors
2

Related Topics

Specialty Route Commands

fix_length

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