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Parasitic capacitances from printed DC operating point of Spectre (with BSIM3v3)

Hi all,

I have a question to ask about BSIM model, I hope it will not take too much time for you to answer this question. Since now I am using a BSIM3.3 0.18-um CMOS model in my work (Cadence, Spectre) and I am wondering about how to figure out the total parasitic capacitances of a transistor. In PSPICE, after I ran a simulation and click on the Probe window to see the output file, I can see a list of small-signal parameters saying that, for example, Cgs = 10 fF (for intrinsic), Cgsov = 20 fF (for overlap capacitance), etc.

However, for BSIM3.3 and for Spectre simulator, I received a set of small-signal parameters after running a simulation, for example, as shown in the attached file. For these parameters, for the capacitances, I don't know how to calculate the total intrinsic and extrinsic capacitances since they are separated into several capacitances. Would you mind to explain me a little bit about this ?

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Jim McMahon over 16 years ago

Mr Wave...
What version of spectre/MMSIM are you using? I am using spectre 7.1 (a fairly recent version) and get the following from Results --> Print --> DC operating point
signal            OP("/I0/NM10" "??")
betaeff             282.703m
cbb                  50.9655f
cbd                 -77.4215a
cbdbi                36.8578f
cbg                 -24.7584f
cbs                 -26.1297f
cbsbi                48.289f
cdb                  -4.34466a
cdd                  36.929f
cddbi               -36.9323f
cdg                 -36.9404f
cds                  15.8045a
cgb                 -24.097f
cgbovl              265.891a
cgd                 -36.5642f
cgdovl               36.926f
cgg                 186.958f
cgs                -126.297f
cgsovl               36.926f
cjd                  36.9353f
cjs                  74.4187f
csb                 -26.8642f
csd                -287.387a
csg                -125.259f
css                 152.411f
gbd                  61.5137u
...etc.

Jim
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Jim McMahon over 16 years ago

Mr Wave...
What version of spectre/MMSIM are you using? I am using spectre 7.1 (a fairly recent version) and get the following from Results --> Print --> DC operating point
signal            OP("/I0/NM10" "??")
betaeff             282.703m
cbb                  50.9655f
cbd                 -77.4215a
cbdbi                36.8578f
cbg                 -24.7584f
cbs                 -26.1297f
cbsbi                48.289f
cdb                  -4.34466a
cdd                  36.929f
cddbi               -36.9323f
cdg                 -36.9404f
cds                  15.8045a
cgb                 -24.097f
cgbovl              265.891a
cgd                 -36.5642f
cgdovl               36.926f
cgg                 186.958f
cgs                -126.297f
cgsovl               36.926f
cjd                  36.9353f
cjs                  74.4187f
csb                 -26.8642f
csd                -287.387a
csg                -125.259f
css                 152.411f
gbd                  61.5137u
...etc.

Jim
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