Using Glaplace component in PSPICE for frequency controlled resistor (2023 Update)

Hello everyone, To model a frequency-controlled resistor, I used the method including a non

-linear laplace form voltage control current source "GLaplace", that some w ebsites and engineerings suggested. I tried with a simple equation, R=1+f, when I do the AC sweep study in th e PSPICE, the model works fine as I attached figure as AC sweep, the resist ance changes from 1 to 101 ohms when frequency changing from 1 to 100 Hz. A nd the voltage crossing that model is consistent with concept. In AC sweep simulation, that model is working ok. However when I simulate that in transient simulation with a simple 100Hz si n wave, the resistance response of model is very inaccurate (the value is f ar away from R=1+100=101 ohms). So I am not sure if those Glaplace model could be used in the transient sim ulation. Did anyone know any information related to that? Any suggestions and comments would be appreciated. Thank you.

Reply to
Chengju Yu
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What are you trying to achieve?

Typically, the point of a frequency dependant resistance is to simulate skin effect resistance for inductors. This can be achieved by an LR ladder network.

If this is your goal, a better option is to use a model that gives the correct 45 degs, 10db/dec characteristic. Pure frequency dependant resistors produce responses that are non real.

e.g.

.SUBCKT SkinEffectResistance_XN !0_A !1_B FMAX=110M K=0.49

  • _SS_Symbol [<System>Functional.ssm] [SkinEffectResister]
*
  • V!1 !1_B B 0 V!0 !0_A A 0
  • skin effect impedance variation with sqrt(F)
  • set F0 to > max fequency of operation .param FX={FMAX/100} .param L={0.1*K/sqrt(FX)} .param R={10*K*sqrt(FX)}
  • R8 Node8 A {R/128} L8 Node8 B {L*128} L1 Node1 B {L} R1 Node1 A {R} R6 Node6 A {R/32} R5 Node5 A {R/16} R4 Node4 A {R/8} R3 Node3 A {R/4} R2 Node2 A {R/2} R0 B A {R} R7 Node7 A {R/64} L2 Node2 B {L*2} L3 Node3 B {L*4} L4 Node4 B {L*8} L5 Node5 B {L*16} L6 Node6 B {L*32} L7 Node7 B {L*64}
  • .ENDS

There is an example in my freebee SuperSpice

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SkinEffectResistance.ssss

That demonstrates this.

Furthermore, there are sets of CoilCraft inductor models that fully implement their inductors using that technique. The Model files should also run directly in LTSpice.

-- Kevin Aylward

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SuperSpice
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Reply to
Kevin Aylward

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