Creating a Freq Resp Mask

Tractor
1

I want to add the FreqResponse test for my device. I see how to add a Mask file for the allowable range, but I don’t see how to generate a Mask file in Analyzer.

When I’m in the Analyzer under the Test Plugins I can run the Amp FreqResponseChirp. The graph generated has a place to export a Mask File, but it is greyed out.

2

You need to do 3 or more freq response tests and add them to the same graph. Then you have the option to create or edit a mask under the Math dropdown menu.
Josh

1 Like
3

Thank you joshmc
Can I do the same in Analyzer mode - put the upper and lower limit lines?

4

Hi @dimitri, yes, once you’ve generated a mask you can load it in the analyzer application the FR context menu (Control + click on Frequency Response button).

If you select Display Pass/Fail then message will be shown in the trace is outside the mask

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5

ok, here is a noise spectrum of BF862, external gain 80 dB

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I went File -> Export Data - > Export Frequency Series -> Saved three traces BF862A,B,C
Then I went Test Plugins -> Graph Tool -> Traces -> Import Trace
I got the error parsing line 6, opev csv in editor, in line 7 was total number of points without #, fixed, imported all three traces,
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(BTW exported data/limits don’t account external gain) generated mask, exported mask, and then did what Matt suggested.
Limits didn’t appear. What I did wrong? Thank you.
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6

When you pull the mask into the QA401 app, you need be in FR mode for it to be applied. But if you are measuring FR, then you can’t really see the noise floor due to the stimulus and other transforms that will be applied. In short, I don’t think you can measure the noise floor with a mask. At some point, the mask function might break out to its own menu and would apply to all modes. That would be useful for letting you measure THD against a mask, for example (eg H2 must be within a range, H3 must be in a different range).

Are you wanting to test noise floor in Tractor or just on the QAAnalyzer app? If Tractor, I’d say do an RMS measurement across your desired bandwidth and then spot check RMS value at a few frequencies across the band.

PS. If you are trying to create a mask in FR mode at some other point, do the following:

  1. Set up your FR params so you are seeing the response you like
  2. Replicate those params in Test Plugins->FreqResponseChirp
  3. Run that at least 3 times, and put all results on the same graph. This should be with different DUT units, or knobs moved slightly simulating operator sloppiness
  4. Then generate a mask after you’ve done your statistical tweaking (in the Graph, see the Math->Add or Edit Mask, and then once you have the spread you want dialed in, in the Graph tool select Traces->Export Mask)
  5. That should import directly into the FR mask fields

A walkthrough of the process is here.