#224 Not converge with simple inverter circuit

closed-works-for-me
Holger Vogt
analyses (40)
5
2013-04-14
2012-12-03
Simon Y.H Chen
No

Dear Friends,

Please check this circuit, it cannot be solved with the latest ngspice code.
Very thanks,
Simon

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.option noacct nopage
.option rshunt=1e12
.subckt inv PWR VSS IN OUT
r1 IN IN_I1 1k
c1 IN_I1 IN_I 1p
*rshunt IN_I VSS 1e18 * it could be converged once open this line
mp OUT IN_I PWR PWR pch l=1u w=2u
mn OUT IN_I VSS VSS nch l=1u w=1u
.model nch NMOS ( level=1 )
.model pch PMOS ( level=1 )
.ends

VDD VDD 0 3
VI I 0 PWL(0 0 100n 3 )
Cap 1 0 5p
xinv VDD 0 I 1 inv
.nodeset v(1)=3

.tran 10n 1000n
.plot tran v(1)
.end

Discussion

  • Holger Vogt
    Holger Vogt
    2012-12-03

    • assigned_to: nobody --> h_vogt
    • status: open --> open-works-for-me
     
  • marcel hendrix
    marcel hendrix
    2012-12-16

    The gates of the two transistors are AC coupled?
    Try it as shown below, where I assume a small
    low-pass filter at IN was actually meant.

    -marcel
    --
    .subckt inv PWR VSS IN OUT
    r1 IN IN_I1 1k
    c1 IN_I1 VSS 1p
    mp OUT IN_I1 PWR PWR pch l=1u w=2u
    mn OUT IN_I1 VSS VSS nch l=1u w=1u
    .model nch NMOS ( level=1 )
    .model pch PMOS ( level=1 )
    .ends

     
  • Holger Vogt
    Holger Vogt
    2013-04-14

    • status: open-works-for-me --> closed-works-for-me