Static Highfanout Check (static_highfanout)

Spectre Syntax

title static_highfanout node=[n1 n2 ...] upth=<value> downth=<value> rcut=<value> <inst=[inst1 inst2...]> <xinst=[xinst1 xinst2...]> <subckt=[subckt1 subckt2....]> <xsubckt=[xsubckt1 xsubckt2....]> <depth=n> error_limit=<value>

SPICE Syntax

.cck title static_highfanout node=[n1 n2 ...] upth=<value> downth=<value> rcut=<value> <inst=[inst1 inst2...]> <xinst=[xinst1 xinst2...]> <subckt=[subckt1 subckt2....]> <xsubckt=[xsubckt1 xsubckt2....]> <depth=n> error_limit=<value>

Description

The static_highfanout check detects MOSFETs that have a gate connected to a high fanout node. The check reports nodes that have a count greater than the specified count.

The results are written to the static.xml file, which can be viewed in a Web browser.

Arguments

node	Nodes to which the check is applied. Default is none.
upth	Defines the ratio of the width of PMOS (pull-up) and the loading of MOSFETs (with gate connection). The load of transmission gate is also considered. The default value is 10.
downth	Defines the ratio of the width of NMOS (pull-down) and the loading of MOSFETs The default value is 20.
rcut	Cuts the resistor having value greater than rcut. The default value is 1e6.
error_limit	Maximum number of errors reported. Default is 10000.
inst	Subcircuit instances to which the check is applied. Default includes all instances (inst=*).
xinst	Subcircuit instances to be excluded from the check. Default is none.
subckt	The instances of the specified subcircuit to which the check is applied. Default includes all subcircuits (subckt=*).
xsubckt	The instances of the specified subcircuits that are excluded from the check. Default is none.
depth	Hierarchy levels (starting from top, instance, or subcircuit scope) to be checked. Default is 8.

Example

Spectre Syntax

chk1 static_highfanout node=["*"] upth=10 downth=20

SPICE Syntax

.cck chk1 static_highfanout node=["*"] upth=10 downth=20

The above statement reports pMOSFETs whose loading-width to driving-width ratio is more than 10. In addition, nMOSFETs whose loading-width to driving-width ratio is more than 20 are reported. The report includes the violation type, displaying if it is a pull-up violation, pull-down violation, or both.

The following is an example of the report that is displayed in the Web browser:

Related Topics

Static Checks

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