Problem with "alter" command

kriszhyan
2013-02-09
2013-06-12
  • kriszhyan
    kriszhyan
    2013-02-09

    I'm using ngspice in the interactive mode. I tried to alter the channel width in a transistor, but got the following error:

    Error: no such model w=  8.0000000e-06 l=  1.8000000e-07.
    

    The circuit is a simple ring oscillator as shown below.

    .model nch nmos ( version=4.4 level=54 lmin=0.1u lmax=20u wmin=0.1u wmax=10u  )
    .model pch pmos ( version=4.4 level=54 lmin=0.1u lmax=20u wmin=0.1u wmax=10u  )
    * Supply
    vdd vdd gnd 1.2 pwl 0 1.2 1e-9 1.2
    rdd vdd vdd_ana 70m
    rgnd    gnd gnd_ana 70m
    * Inverter
    mp1 inv1    inv3    vdd_ana vdd_ana pch w=10u l=0.18u
    mn1 inv1    inv3    gnd_ana gnd_ana nch w=10u l=0.18u
    mp2 inv2    inv1    vdd_ana vdd_ana pch w=10u l=0.18u
    mn2 inv2    inv1    gnd_ana gnd_ana nch w=10u l=0.18u
    mp3 inv3    inv2    vdd_ana vdd_ana pch w=10u l=0.18u
    mn3 inv3    inv2    gnd_ana gnd_ana nch w=10u l=0.18u
    * Buffer out
    mp4 bout    inv3    vdd_ana vdd_ana pch w=10u l=0.18u
    mn4 bout    inv3    gnd_ana gnd_ana nch w=10u l=0.18u
    .tran 0.005n 100n
    

    The command I used is "alter @mn1=8u".  I'm using ngspice-25. Does anyone know why I get the error and how I can fix it?

    Thanks in advance.

     
  • Holger Vogt
    Holger Vogt
    2013-02-13

    kriszhyan,

    in fact this is a bug in ngspice-25. We are looking into it.

    Holger

     
  • Holger Vogt
    Holger Vogt
    2013-02-23

    There is now an update to ngspice git which solves the problem.

    Holger