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  3. how to print node-to-node capacitance?

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how to print node-to-node capacitance?

flying
flying over 14 years ago

I'm trying to find a way in spectre to calculate the capacitance between every two terminals of a transistor (I hope it exists).

In Spectre users' Guide, info could be used to print node-to-node capacitance.

********************************************************************************
  Inputsweep1 sweep param=dc dev=vg start=Vgnd stop=Vdd step=0.05 {
  Inputsweep2 dc param=dc dev=vd start=Vgnd stop=Vdd step=0.05
  }
  sweepInfo info what=captab where=file file="capNodes" detail=nodetonode

*************************************************************************************8

I expected I could get a capacitance list for every vd and vg combination,however unfortunately I just got the following text:

My questions are:

1: what's the meaning of 'n1:dbnode',  'n1:dbnode', and 'n2:dbnode'? I didn't have instance 'n2' inthe netlist...

2: how to get the node-to-node capacitances with respect to terminal voltages?

**********************************************************

******************************
 3 Capacitance Table `sweepInfo':
 4 ******************************
 5 Capacitance values computed in info analysis `sweepInfo' at T = 27 C.
 6
 7 n2:dbnode : n1:dbnode   fixed=0           , variable=53.4296 a   ,
sum=53.4296 a   .
 8 n1:dbnode : 0   fixed=0           , variable=0           ,
sum=0           .
 9 n1:dbnode : n1:int_b    fixed=-0          , variable=0           ,
sum=-0          .
 10 n1:dbnode : vd  fixed=-0          , variable=53.4296 a   ,
sum=53.4296 a   .
 11 n1:dbnode : vss fixed=-0          , variable=0           ,
sum=-0          .
 12
 13 n1:int_b : n1:int_b     fixed=576e-21     , variable=8.87769 a   ,
sum=9.45369 a   .
 14 n1:int_b : 0    fixed=0           , variable=0           ,
sum=0           .
 15 n1:int_b : n1:dbnode    fixed=-0          , variable=0           ,
sum=-0          .
 16 n1:int_b : n1:int_g     fixed=576e-21     , variable=10.777 a    ,
sum=11.353 a    .
 17 n1:int_b : n1:sbnode    fixed=-0          , variable=0           ,
sum=-0          .
 18 n1:int_b : vd   fixed=-0          , variable=-423.98e-21 ,
sum=-423.98e-21 .
 19 n1:int_b : vg   fixed=-0          , variable=0           ,
sum=-0          .
 20 n1:int_b : vs   fixed=-0          , variable=-1.47531 a  ,
sum=-1.47531 a  .
 21 n1:int_b : vss  fixed=-0          , variable=0           ,
sum=-0          .
 22
 23 n1:int_g : n1:int_g     fixed=53.6817 a   , variable=91.0626 a   ,
sum=144.744 a   .
 24 n1:int_g : 0    fixed=0           , variable=0           ,
sum=0           .
 25 n1:int_g : n1:int_b     fixed=576e-21     , variable=247.452e-21 ,
sum=823.452e-21 .
 26 n1:int_g : vd   fixed=26.5528 a   , variable=16.6791 a   ,
sum=43.232 a    .
 27 n1:int_g : vg   fixed=-0          , variable=0           ,
sum=-0          .
 28 n1:int_g : vs   fixed=26.5528 a   , variable=74.136 a    ,
sum=100.689 a   .
 29
 30 n1:sbnode : n1:sbnode   fixed=0           , variable=113.911 a   ,
sum=113.911 a   .
 31 n1:sbnode : 0   fixed=0           , variable=0           ,
sum=0           .
 32 n1:sbnode : n1:int_b    fixed=-0          , variable=0           ,
sum=-0          .
 33 n1:sbnode : vs  fixed=-0          , variable=113.911 a   ,
sum=113.911 a   .
 34 n1:sbnode : vss fixed=-0          , variable=0           ,
sum=-0          .
 35
 36 vb : vb fixed=0           , variable=0           , sum=0           .
 37 vb : 0  fixed=0           , variable=0           , sum=0           .
 38
 39 vd : vd fixed=26.5528 a   , variable=72.2212 a   , sum=98.774 a    .
 40 vd : 0  fixed=0           , variable=0           , sum=0           .
 41 vd : n1:dbnode  fixed=-0          , variable=53.4296 a   ,
sum=53.4296 a   .
 42 vd : n1:int_b   fixed=-0          , variable=3.45385 a   ,
sum=3.45385 a   .
 43 vd : n1:int_g   fixed=26.5528 a   , variable=31.758 a    ,
sum=58.3108 a   .
 44 vd : vg fixed=-0          , variable=0           , sum=-0          .
 45 vd : vs fixed=-0          , variable=-16.4203 a  , sum=-16.4203 a  .
 46
 47 vdd : vdd       fixed=0           , variable=0           ,
sum=0           .
 48 vdd : 0 fixed=0           , variable=0           , sum=0           .
 49
 50 vg : vg fixed=0           , variable=0           , sum=0           .
 51 vg : 0  fixed=0           , variable=0           , sum=0           .
 52 vg : n1:int_b   fixed=-0          , variable=0           ,
sum=-0          .
 53 vg : n1:int_g   fixed=-0          , variable=0           ,
sum=-0          .
 54 vg : vd fixed=-0          , variable=0           , sum=-0          .
 55 vg : vs fixed=-0          , variable=0           , sum=-0          .
 56
 57 vs : vs fixed=26.5528 a   , variable=170.151 a   , sum=196.704 a   .
 58 vs : 0  fixed=0           , variable=0           , sum=0           .
 59 vs : n1:int_b   fixed=-0          , variable=5.17639 a   ,
sum=5.17639 a   .
 60 vs : n1:int_g   fixed=26.5528 a   , variable=48.5276 a   ,
sum=75.0804 a   .
 61 vs : n1:sbnode  fixed=-0          , variable=113.911 a   ,
sum=113.911 a   .

********************************************************************************** 

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  • AndrewMac
    AndrewMac over 14 years ago

     

    If you just want to see the device capacitances of a single transistor, you don't need the capacitance table.  Just find the dc properties in the results browser.  You can plot sweep results this way too.

     I don't know what you mean about "Cgs=dQg/dVs" and "cgs=dQgs/dvgs".

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  • AndrewMac
    AndrewMac over 14 years ago

     

    If you just want to see the device capacitances of a single transistor, you don't need the capacitance table.  Just find the dc properties in the results browser.  You can plot sweep results this way too.

     I don't know what you mean about "Cgs=dQg/dVs" and "cgs=dQgs/dvgs".

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