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RC extraction - how does look like?
- Thread starter ivlsi
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saurabhr8here
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RC extraction from a tool like Synopsys Star-RC will spit out an HSPICE SUBCKT netlist with Resistances and capacitances corresponding to the different layers in your layout in addition to the transistors. It might include the area/perimeter of your transistors but the best estimate of your net area should come from looking at layout directly. RC extraction is useful for characterization of your cells since it includes parasitic resistances/capacitances due to contacts and wires. StarRC has the capability to show coupling capacitance report, lump all capacitance to ground, do R only or C only capacitance etc. The general output format of the extracted netlist is something like this:
.SUBCKT GATENAME PINS
R1 node 1 node 2 Rval1
R2 node 2 node 3 Rval2
C1 node 1 node 4 Cval1
.
.
.
.
M1 nmos node1 node2 node3 W L ....
M2 pmos node4 node2 node5 W L ....
.ENDS
In the above example I am just trying to give an example of what it'd look like, please do not check for accuracy regarding node/pin names
.
.SUBCKT GATENAME PINS
R1 node 1 node 2 Rval1
R2 node 2 node 3 Rval2
C1 node 1 node 4 Cval1
.
.
.
.
M1 nmos node1 node2 node3 W L ....
M2 pmos node4 node2 node5 W L ....
.ENDS
In the above example I am just trying to give an example of what it'd look like, please do not check for accuracy regarding node/pin names
.
ivlsi
Advanced Member level 3
As for the Resistance and Capacitance, are they always "parasitic"? I mean, there are SDF and SPEF. As for the RC-extraction for SDF, are the resistance and capacitance still parasitic?
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saurabhr8here
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I mainly deal with transistor models, HSPICE simulations and extraction. Hence, I am not very familiar with flows beyond extraction and someone else might be able to provide you with detailed information regarding SDF/SPEF. As far as I understand, SPF file is what you get after RC extraction. You can use it in tools like PrimeTime to get SDF, which has the cell delay information. This is calculated using the information in the SPF file (I think).
The R and C's are not necessarily parasistic in extraction, they would include interconnect RC as well. The parasitic components are from the FEOL (Front-End-of-Line) and MOL(Middle-of-Line) layers like local interconnects, contact R and fringing C.
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