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R&S NGE100 voltage jumping around
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RBBVNL9:

--- Quote ---It is not stated explicitly (as far as I can see), but I would assume that the programming accuracy is specified with no load.

--- End quote ---

Mmm. That’s an interesting point. I once understood that ripple and noise specs are usually provided for full load (after all, in a classical design, it is under load that capacitors discharge and ripple emerges). Would program accuracy be different in that respect?


--- Quote ---So you would have to allow for another 0.1%+20mV due to load regulation.
--- End quote ---

Not sure where you take that number from. In the specs, I see that number for "Readback accuracy" but I understand that number to reflect the values shown on the voltmeter on the front panel, but that would be something different.
switchabl:
I may be wrong. But it seems to be the case for Agilent power supplies. In any case, with datasheets I usually assume that all error sources may add up unless otherwise stated. Arguably if it included everything, we could just call it "output accuracy" and not list load/line regulation at all  :-//

Load regulation is listed on p.8 (https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/service_support_30/NGE100B_bro_en_5216_1370_32_v0100_120dpi.pdf)
< 0.1% + 20mV for a load change from 10% to 90%.
RBBVNL9:

--- Quote ---Load regulation is listed on p.8 (https://scdn.rohde-schwarz.com/ur/pws/dl_downloads/dl_common_library/dl_brochures_and_datasheets/pdf_1/service_support_30/NGE100B_bro_en_5216_1370_32_v0100_120dpi.pdf)
< 0.1% + 20mV for a load change from 10% to 90%.
--- End quote ---

Oh yes, you are right, I see that now. Overlooked it. It also has the "±" sign.
justanothername:
Programming accuracy: This is (in my understanding) no specfication that describes the dynamic behavior of the unit. It is what you get in voltage when you set a voltage.
I'm thinking about linearity of the DAC, not low frequency noise of the output. So for instance, if you want to set 4V you may get 4.034V because of (shitty) DAC but this should be stable within noise and load regulation specification.
Maybe I'm just completely wrong here.
It's the accuracy vs precision thing:
https://commons.wikimedia.org/wiki/File:Accuracy_and_Precision.svg
RBBVNL9:
@justanother name: this is an interesting thought.

In this article, the same is explained in the context of a measurement instrument. A recommended read. In analogy with your picture with a target, for a 'perfect' measurement all dots(which are measurements over time) are exactly on the bull's eye.

Yet, my interpretation for a PSU is as follows: the provided value explains that we were to connect the perfect meter above to the output of the PSU, then at any time, the readings of that perfect meter would be within the 'inner circle of your target'. This requires:
- an internal measurement function in the PSU that is sufficiently accurate to reach that goal,
- an internal measurement function in the PSU that is sufficiently precise to reach that goal (one might average a bit over time to facilitate this),
- an internal mechanism that is good enough to make the actual output track the internal measurements within the given specification.

My take...


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