Can LTSpice's .ac statement sweep secondary values?

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SUMMARY

The discussion focuses on performing frequency domain analysis in LTSpice using the ".ac" statement while simultaneously varying secondary component values, such as resistors. The user seeks a method to achieve this without executing separate sweeps for each resistor value. A solution was provided by a forum member, helmutsennewald, who shared an example of a frequency-dependent resistor using Laplace equations, specifically through the use of G-source and Gpoly components. The provided LTSpice file can be accessed via a Yahoo group link for practical implementation.

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  • Understanding of AC analysis and the ".ac" statement
  • Knowledge of Laplace transforms and their application in circuit analysis
  • Experience with creating and modifying circuit schematics in LTSpice
NEXT STEPS
  • Explore the use of G-source and Gpoly components in LTSpice for advanced simulations
  • Learn how to implement Laplace equations in LTSpice for frequency-dependent components
  • Research the ".step" command in LTSpice for multi-variable sweeps
  • Investigate additional resources on frequency domain analysis techniques in circuit design
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Electrical engineers, circuit designers, and simulation specialists looking to enhance their LTSpice skills, particularly in frequency-dependent analysis and multi-variable circuit simulations.

Landru
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If you have a simple circuit with an AC voltage, you can do a frequency domain analysis with a statement like ".ac lin 500 10 10000" and it will run the gamut from 10Hz to 10000Hz, but is there a way to have a second variable also scale in tandem, say the value of a resistor?

I'm aware that the step command exists, and it allows you to test multiple values, but that's one full sweep for each of those values, one at a time, and what I desperately need to is to have a second, or maybe even a third component value change along with the frequency.

Can this be done?
 
I asked on the LTspice yahoo group; how could I make a sweep frequency dependent resistor and received the following file from the Guru helmutsennewald.
helmutsennewald said:
May 6 6:26 PM Hello, I have uploaded an example of a frequency dependent resistor for .AC-simulations.

Frequency_dependent resistor.asc
https://groups.yahoo.com/neo/groups/LTspice/files/ Temp/

I have used Laplace equations.

G-source
Laplace=1/abs(s/(2*pi))

Gpoly
LAPLACE {V(3)*V(2)} {1/abs(s/(2*pi))}Helmut

Attached is the file.
Remove the .txt extension to make it back into a .asc file.
 

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