candence 阻抗匹配设定

Posted 2020-10-11 Temo2015

IMPEDANCE_RULE

The IMPEDANCE_RULE property, attached to a net, specifies an impedance restriction between any two pins on a net or between any pin and Tpoint connection on a net. This property is used by DRC checking and routing.

If a connection has an impedance constraint specified by both an IMPEDANCE_RULE property and an electrical constraint set, the IMPEDANCE_RULE value is used. Use Constraint Manager for pin-pairs.

The format of the IMPEDANCE_RULE property in the $A_PROPERTIES section of a netlist is

IMPEDANCE_RULE{ALL:ALL:impedance:tolerance:}... ; netname=A:B:C:D

A:起点

B:终点

C:阻抗大小

D:阻抗的误差大小

	ALL:ALL	Specifies the checking of impedance of everyconnect line (cline) segment in the net.
impedance	Required. Specifies the impedance constraint value in ohmsexpressed as a decimal number.
tolerance	Specifies the tolerance for an impedance value specified either as avalue in ohms or a percentage. You must follow a percentage with a % (percent sign). If you do not specify a value, 2% is assumed.
netname	Specifies the name of the net to which the impedance applies.

例如：

IMPEDANCE_RULE= ALL:ALL：50ohm：10ohm

（设定走线的阻抗是50ohm，误差正负10ohm）

IMPEDANCE_RULE= ALL:ALL：50ohm：20%

（设定走线的阻抗是50ohm，误差正负20%）

IMPEDANCE_RULE= U1.1:R1.1：50ohm：10OHM

（设定走线U1.1到R1.1的阻抗是50ohm，误差正负20%）

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来自为知笔记(Wiz)