Intel® Quartus® Prime Pro Edition User Guide: Scripting

ID 683432
Date 12/13/2021
Public

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3.1.28.22. set_timing_derate (::quartus::sdc_ext)

The following table displays information for the set_timing_derate Tcl command:

Tcl Package and Version

Belongs to ::quartus::sdc_ext

Syntax set_timing_derate [-h | -help] [-long_help] [-cell_delay] [-early] [-late] [-net_delay] [-operating_conditions <operating_conditions> ] <derate_value> [ <cells> ]
Arguments -h | -help Short help
-long_help Long help with examples and possible return values
-cell_delay Specifies that derating factors are only to apply to cell delays
-early Specifies the minimum derating factor. This factor specifies how early the signal can arrive
-late Specifies the maximum derating factor. This factor specifies how late the signal can arrive
-net_delay Specifies that derating factors are only to apply to net delays
-operating_conditions <operating_conditions> Operating conditions Tcl object
<derate_value> Timing derate value
<cells> List of cell type objects
Description

Sets the global derate factors for the current design. The maxmimum and minimum delays of all timing arcs in the design are multiplied by the factors specified with the -late and -early options respectively. Only positive derate factors are allowed. If neither the -cell_delay nor -net_delay option is used, the derating factors apply to both cell and net delays. For net delay derates, the derate factor is applied to nets driven by matching cells. Specifying a derate value of less than 1.0 for the -late option or a derate value of greater than 1.0 for the -early option reduces delay pessimisim, which might lead to optimistic results from timing analysis. The effect of set_timing_derate command is deferred until the next time update_timing_netlist is called. To reset derate factors to original values, use the reset_timing_derate command. This assignment is for timing analysis only, and is not considered during timing-driven compilation.

Example Usage
set_timing_derate -early 0.9 [get_cells *]
set_timing_derate -late 1.1 [get_cells *]
Return Value Code Name Code String Return
TCL_OK 0 INFO: Operation successful
TCL_ERROR 1 ERROR: Option -<string> has illegal value: <string>. Specify a legal option value.
TCL_ERROR 1 ERROR: Timing netlist does not exist. Use create_timing_netlist to create a timing netlist.

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