# Frequency dependent resistor in PSpice

Discussion in 'General Electronics Discussion' started by Bala_01, May 31, 2016.

1. ### Bala_01

6
0
May 30, 2016
Think a simple case. I want to create frequency dependent resistor R1. The value of R1 is as follows:
at 1 MHz -> R1 = 2
at 5 MHz -> R1 = 10
at 10 MHz -> R1 = 20
at 100 MHz -> R1 = 200
Thant means R1 is a function of frequency where R1=2* Frequency. Consider only the numerical value of frequency not unit. How can I implement in Pspice ?

Best regards,
Bala

2. ### davennModerator

13,810
1,944
Sep 5, 2009
pretty sure there's no such thing as a frequency dependent resistor
in my 40+ yrs of electronics have never heard of one

so what are really trying to achieve ??

3. ### Bala_01

6
0
May 30, 2016
Hi,
I have found the solution. It can be done with Laplace transformation.
************ Test ***************
.subckt Test01
+ 1 2
*
*
G_Rvar1 1 2 LAPLACE { V(1)} {1 /((1/K1)*(s/(2*PI)))}
*
.param K1=1
.param PI =3.141592654
**********
**********
**********K1=1 when Frequency in Herz
**********K1 =1e6 when Frequency in MHz
**********
**********
*
*
.ends

I need this info to test a HV Filter.

Thanks,
Bala

4. ### LvW

604
146
Apr 12, 2014
Perhaps, this is not what the OP (Bala_01) needs - but there is a very versatile active circuit called "Frequency-Dependent Negative Resistor (FDNR) " consisting of two opamps. Such a device is extensively used in active filters and harmonic oscillators. It is a special version of the universal GIC circuit.

5. ### Alec_t

2,949
803
Jul 7, 2015
Can't you just right-click on the resistor value in the schematic and set the value to {2*frequency} ? Then add a directive .param frequency=3meg (or whatever).

Bala_01 likes this.
6. ### Bala_01

6
0
May 30, 2016
I need a Pspice netlist model which I can import in CST DS.

7. ### CDRIVEHauling 10' pipe on a Trek Shift3

4,960
651
May 8, 2012
Ha, I know that this is not what you meant but attempting to use a wire-wound resistor as a 50Ω RF Dummy-Load comes close to fitting the definition.

Chris

Arouse1973 likes this.