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Modeling >> Passive Devices >> Attributes depending on the value of voltages and currents
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Message started by Emmanuele on Oct 15^th, 2009, 5:02am

Title: Attributes depending on the value of voltages and currents
Post by Emmanuele on Oct 15^th, 2009, 5:02am

HI to everybody.
I'm using Design Entry HDL (in Cadence SPB 16.01), an upgraded version of PSpice.
I would like to know if it's possible to define the value of an attribute (say, the resistance of a resistor) depending on the istantaneous value of a voltage or a current in the circuit.
I know that it's possible to define values which depend on constants, or fixed parameters; but I'd like to define comething more complex.
For instance, I'd like to define a resistor with a resistance depending on a function of the integral of the power dissipated in its (ie R*I^2).
Any suggestions?
Thanks a lot,
Emmanuele

Title: Re: Attributes depending on the value of voltages and currents
Post by Geoffrey_Coram on Oct 20^th, 2009, 5:17am

I'd write the model in Verilog-A.

If you're stuck in PSpice without Verilog-A, I expect you could write a subckt with dependent sources that measure the I and V of the resistor, make a current that's equal to I*V, and dump that onto a capacitor; the instantaneous voltage on the cap is then the integral of the dissipated power. (You'll need a resistor to ground for the dc solution, but you can make it very large if you're not modeling the heat transfer away from the device.)