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Hspice warning: singular supplies terminated to 1 meg resistor

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royalty

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Hi guys,

I have a varactor model and i want to simulate ac resistance of this device. When I run simulation, it gives result as 1 meg for every DC point at the same frequency. I examined log file and i saw a warning like this:

the following singular supplies were terminated to 1 meg resistor
(input.spi:25)v7 0:dc defined in subckt 0 0:0 defined in subckt 0

What is the problem in this situation? Indeed, my assumption is the simulator locate resistor between plus terminal of supply and ground, to converge because it does not match terminal number of subckt in the model file with terminal number of CDF.

Anybody has an idea about this warning?

Regards

royalty.
 

erikl

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Anybody has an idea about this warning?

A warning is a warning, is just a warning. If it doesn't clash with your simulation result, forget about it.
 

royalty

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A warning is a warning, is just a warning. If it doesn't clash with your simulation result, forget about it.

Unfortunatelly, the warning leads to incorrect results in my simulation. Because, hspice automatically terminates voltage source with 1 meg resistor. I am trying to simulate impedance of varactor. Because of termination with 1 meg resistor, the result is always equal to 1 meg.
 

dick_freebird

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It wants to calculate current around every loop and your
"singular" (unconnected pin) supplies can't be processed
that way. So it added a couple of resistors to make do.

You could apply a higher value resistor explicitly.

Your impedance with a shunt voltage source should be zero.
Adding 1Mohm shunt ought to affect it not at all. There is
something not right here. Probably relating to approach.
 

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