Frequency Dependent Resistance

[Jason Dugas]

I'm looking for a way to model a frequency dependent resistor in PSPICE
(ORCad). I have some empirical data for a load which changes resistance
(real part of impedance) with frequency. The changes are non-linear and are
not monotonic. Prefer to use a lookup table if that is a possibility.
Thanks for any help you can provide.

Jason

 

[Charles Edmondson]

Jason Dugas wrote:

I'm looking for a way to model a frequency dependent resistor in PSPICE
(ORCad). I have some empirical data for a load which changes resistance
(real part of impedance) with frequency. The changes are non-linear and are
not monotonic. Prefer to use a lookup table if that is a possibility.
Thanks for any help you can provide.

Jason


Hi Jason,

Take a look at the Gfreq device. If you think of a resistor as a
voltage controlled current source (i.e. current depends on voltage,
right!) then wire one of these with the two 'top' pins (in+ and out+)
together, and the two 'bottom' pins (in- and out-) together, and you
have a device that senses the voltage across itself. You then enter
your table of values in it, and it should work!

--
Charlie
--
Edmondson Engineering
Unique Solutions to Unusual Problems

 

[qrk]

On Thu, 1 Apr 2004 23:19:33 -0600, "Jason Dugas" <kb5urq@hotmail.com>
wrote:

I'm looking for a way to model a frequency dependent resistor in PSPICE
(ORCad). I have some empirical data for a load which changes resistance
(real part of impedance) with frequency. The changes are non-linear and are
not monotonic. Prefer to use a lookup table if that is a possibility.
Thanks for any help you can provide.

Jason

The following work in PSpice and LTSpice. The data is entered as
complex admittance. You don't need to use a subcircuit as shown in the
example. There is also a method of using a voltage controlled voltage
source and a current meter (V source) if you want to enter the data as
complex impedance. See
http://www.ecircuitcenter.com/Circuits/vc_resistor1/vc_resistor1.htm

*Data format: Freq(Hz) G(mhos) B(mhos)
..SUBCKT XDCRZ 1 2
G1 2 1 FREQ {V(2,1)}= R_I (
+ 130000.000000 1.2703m 11.012m
+ 131567.000000 1.2536m 11.201m
+ 133152.890625 1.3147m 11.431m
+ 134757.890625 1.3671m 11.603m
+ 136382.234375 1.3512m 11.874m
+ )
..ENDS XDCRZ


Regards, Mark