.bode or .meas FRA? What is better to use?


What is best to stick with and to use: .bode or .meas FRA? Because I see that only these 2 variants are available for using for frequency response analysis in qspice. Applications target: smps.

I have conducted a study on how to use the .bode command and included a simple comparison of .meas FRA in the last section.
Qspice/Guideline/Qspice - Bode Frequency Response Analysis (.bode).pdf at main · KSKelvin-Github/Qspice

Professor Marcos Alonso (@marcos.uniovi) has a YouTube channel with tutorials on frequency response in SMPS using Qspice. (look for Qspice#4 and Qspice#5)
Marcos Alonso - YouTube

@physicboy has his own project of FRA analyzer
4-Channel FRA analyzer - QSPICE - Qorvo Tech Forum

I know these details. Is better to use .bode than .meas FRA?

Personally, I prefer using the .bode command, but there are different opinions within the community. I believe both methods can accomplish the task; it ultimately depends on which method you are more familiar with. (.bode possibly quicker but without time domain data for user to review is a disadvantage)

Me too, I like .Bode command. Do You think that can be situations where Bode command can fail, or to be hard to get correct results? Someone also say that Bode command is quicker but dirtier. What do You belive about this thing?

if you are looking for speed, .bode is your better bet.
however, the accuracy is not as good as .meas fra…and in some specific cases, the algorithm may fail.

between .meas fra and my own implementation. the difference is on the detail implementation.
.meas fra perform the computation on post processing, thus you need to store all the waveform data.
my design perform the computation on the simulation runtime, thus you dont need to store any waveform.

accuracy wise .meas fra and my design should be similar. However, for simulation system with long time constant, you may prefer to use my design as post processing on GB of data often result in your PC crashing.

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