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DUT delay


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Hi @Fabio FZ

Could you provide more detail about the experiment setup? software and hardware...

You can inspect the captured signals under View/ Time.
Your signal may be distorted by exceeding the Wavegen current limits, your circuit may need longer settle time for each step....
image.thumb.png.d5e138f1d33a251b65143f634912199d.png

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Actually I'm wondering what you consider "misleading" about your result. This is what a network analyzer will show when you set it up as you did.

Some thoughts:

- use a linear frequency axis instead of logarithmic (and a linear frequency sweep, at least on a conventional CW-swept VNA)

- you need a higher density of points so the eye can unwrap the phase in the 6 kHz region (for an algorithm this might be even enough but it's visually distracting). Right now, it looks like the direction changes but that's a visual artifact from connecting the dots within a single 360-degree zone.

 

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Thanks Attila , I am measuring a DSP that have a 2ms latency ( propagation delay ) - I what to check the output phase  of this DSP using the input as a reference . Due to the DUT ( DSP ) delay the phase isn't correct and the results are what I would expect  . On other types of measuring system  I am able to measure this latency and compensate on the software for example

Rgsd Fabio

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On 11/8/2020 at 5:32 AM, xc6lx45 said:

Actually I'm wondering what you consider "misleading" about your result. This is what a network analyzer will show when you set it up as you did.

Some thoughts:

- use a linear frequency axis instead of logarithmic (and a linear frequency sweep, at least on a conventional CW-swept VNA)

- you need a higher density of points so the eye can unwrap the phase in the 6 kHz region (for an algorithm this might be even enough but it's visually distracting). Right now, it looks like the direction changes but that's a visual artifact from connecting the dots within a single 360-degree zone.

 

Thanks xc6lx45 - you are correct , using more points will sort out the phase artifact -but on this case I am looking to see the a flat phase curve by compensating the DUT latency ( I am measuring in to out phase )

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On 11/11/2020 at 5:59 PM, attila said:

Hi @xc6lx45 @Fabio FZ

Is this "electrical length correction" expressed in time?
I think I can add such option to the NA.

 

Yes, it's just a roundabout way to express it via the speed of light (usually with the effective epsilon_r of the dielectric as extra parameter, then it's really a physical line length).

For AD frequency range, using time seems a good choice, IMHO.

For example, taking a random Rohde manual: https://cdn.rohde-schwarz.com/pws/dl_downloads/dl_common_library/dl_manuals/gb_1/z/zvl_1/ZVL_Operating_en_09.pdf

Page 137 "Phase Delay/El. Length"

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