Standard Parasitic Exchange Format (SPEF) is an IEEE standard for representing parasitic data of wires in a chip in ASCII
ASCII
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of wires in a chip are known as parasitic data. SPEF is used for delay calculation
Delay calculation
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of a chip which eventually determines its speed of operation.
SPEF is most popular specification for parasitic exchange between different tools of EDA
Electronic design automation
Electronic design automation is a category of software tools for designing electronic systems such as printed circuit boards and integrated circuits...
domain during any phase of design.
The specification for SPEF is a part of standard 1481-1999 IEEE Standard for Integrated Circuit (IC) Delay and Power Calculation System.
SPEF syntax is roughly:
SPEF "IEEE 1481-1998"
DIVIDER /
DELIMITER :
BUS_DELIMITER [ ]
T_UNIT 1 NS
C_UNIT 1 FF
R_UNIT 1 OHM
L_UNIT 1 UH
D_NET NetA 1.0
CONN
P A
P B
I X:Y
A 2.47
B 9.8
X:Y 1.2e-1
A B 4.76e3
D_NET NetB 0.0
END
...
And repeat (include *END) for other nets.
In order to reduce file size, aliasing is possible, using a name-map:
NAME_MAP
0 ALongWord
1 BLongerWord
2 CStillLongerWord
...
These symbols (including the *) can then be substituted for the longer words anywhere.
Note: SPEF is not the same as SPF (including DSPF and RSPF). Detailed Standard Parasitic Format is a very different format, meant to be useful in a SPICE
SPICE
SPICE is a general-purpose, open source analog electronic circuit simulator.It is a powerful program that is used in integrated circuit and board-level design to check the integrity of circuit designs and to predict circuit behavior.- Introduction :Unlike board-level designs composed of discrete...
simulation. For example, NET sections do not have endings, and comments should start with two asterisks.
A brief syntax of the DSPF format is as shown:
DSPF 1.0
DIVIDER /
DELIMITER :
BUS_DELIMITER [ ]
|GROUND_NET NetName
.SUBCKT
NET NetName NetCap
|I(InstancePinName InstanceName PinName PinType PinCap X Y)
|P(PinName PinType PinCap X Y)
|S(SubNodeName X Y)
.ENDs
.END
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