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Creating a "virtual short" in simulations

jehh

Hi,

In my APS simulations I have added some inductors from the analogLib (ind), to represent the effect of bond wires. These slow down the simulation, but is necessary in order to understand some dynamics.

In some situations I do not wishto test these dynamics, and was wondering if it is possible to specify that 'all inductors are shorted', or something of similar effect?

Br,
JEHH

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  • Frank Wiedmann

    From typing "spectre -h options" at the command line:

    102 lshort=0 H Fixed value inductors with L<=lshort are shorted.
    lshort can additionally be applied to variable value
    inductors using the option 'short_cut_var_elem=yes'.

  • jehh
    in reply to Frank Wiedmann

    Thank you - this seems like the right path.

    However, I try to specify lshort=10n, under additional arguments in the spectre simulator options, and then run a transient simulation. However, it doens't seem to short the inductor. Am I using the lshort correctly, or did I misinterpret?

  • ShawnLogan
    in reply to jehh

    Dear jehh,

    I was going to suggest a slightly different approach. Have you considered including an ideal resistor in parallel with each inductor with a value set by a variable, for example, "rshort"? In this fashion, when you want to include the inductors in your simulation, you set "rshort" to very large value. For  simulations where you do not wish to include the inductors, you set "rshort" to a very small value (1 milliohm, as an example).

    Shawn

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  • ShawnLogan
    in reply to jehh

    Dear jehh,

    I was going to suggest a slightly different approach. Have you considered including an ideal resistor in parallel with each inductor with a value set by a variable, for example, "rshort"? In this fashion, when you want to include the inductors in your simulation, you set "rshort" to very large value. For  simulations where you do not wish to include the inductors, you set "rshort" to a very small value (1 milliohm, as an example).

    Shawn

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