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Dynamic nodesets on DC Sweeps

Johanny Saenz

Hi all!

I'm having difficulties to find the desirable OP point during a  DC sweep  with a comparator that use a amux a resistor string to generate the hysteresis. The simulator find most of the time a VDD/2 stable operation point.

I'm defining nodeset statements, which are only valid to the OP point calculation but as DC sweeps the input, it makes the output to trigger and the nodeset statement is not longer valid. 

Does the nodeset statement consider only for OP? Or it is also considered for each step of DC sweep?

Can I define a nodeset dependent on a parameter condition (ternary operator), something like (vn_par>vref_par)?0:avdd_par

Thanks!

  • Andrew Beckett

    Nodesets are only used at the first point of any swept analysis - they are used to find the operating point or initial transient solution (in the case of a transient). So if you do a DC operating point, node sets are used for that. Or they're used for the DC before an AC analysis. Or a DC before a transient (if you give a readns, say), or for the DC operating point at the beginning of a sweep.

    Yes, you can define a nodeset using a condition such as you've given.

    Regards,

    Andrew.

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