Band pass filter simulation with complex impedance on input

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Kevil

Joined Jun 28, 2020
134
Any idea how to simulate SAMR34 RFO_HF 868 MHz complex output impedance 36.0+j36.5 to see the correct 868 MHz bandpass filter value in LTspice? The simulation shows peek at 823 MHz (in SPICE Error log).

868_MHz_Matching.png

SAMR34_Matching.png
 

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Papabravo

Joined Feb 24, 2006
18,400
Any idea how to simulate SAMR34 RFO_HF 868 MHz complex output impedance 36.0+j36.5 to see the correct 868 MHz bandpass filter value in LTspice? The simulation shows peek at 823 MHz (in SPICE Error log).

View attachment 259560

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Is this what you are looking for?
BTW: I can't claim credit for this technique. It was shown to me by @Bordodynov
Also I may or may not have done it correctly. I'm guessing the answer is that I did not, because the measurement failed.

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Papabravo

Joined Feb 24, 2006
18,400
I think the component models you need for LTspice to show what you expect need to be more complicated than lumped elements. I think they need parasitics to adequately model the behavior of a real circuit.

Q: What happens if you make the whole network out of resistors with both real an imaginary parts?

In order to make this accurate you might have to sweep each component separately.
 
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