On Thu, Feb 27, 2025 at 04:20 AM, Robert wrote:
5pF is not unreasonable for the circuit I'm modelling,
Keep in mind, 5pF will be added to
every single node in the circuit.? If you have an IC, which it appears you do (LT1375HV, maybe others), then it is added to
every internal node of those models too.? It could
significantly alter the simulation.
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Helmut's recommendation in the FAQ file was CSHUNT = 1e-15, and not larger.? That is 1 fF (femtoFarad), or 0.001 pF.? He also noted: "Be very careful with this option. It may disturb your circuit."
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IMO, 0.5 pF is not unreasonable for external pins that land on PCB pins (oops!) pads, but it is much too large for anything internal.? Also remember that many most SPICE models are not physical, and disturbing an internal node like this might change its calculations significantly.
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Andy
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