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Hi Klaus, but then you would probably not be able to design this circuit since there are too many unknows for your method to even get started.
Only doable math has been done in this case.
And how would any math sort out the potential grounding issues?
Best regards
X
Thanks FvM and Klaus.
This is not about EMC but rather about measuring low frequency signals in the higher nV and uV range.
I am just not sure what to do with this. That is despite the fact that I designed some pro audio suff in the past. It never had processors and digital stuff mixed with...
Hello,
I am scratching my head again regarding grounding of digital and analogue parts
I have split ground planes for digital ground DGND and analogue ground AGND, joining only at the power supply regulator.
I now have a DAC DAC121S101 chip that will supply a voltage into an analogue circuit...
Hi Dana,
I am going to look into the SOC you mentioned. SOC = System on Chip ?
My search shows that SOC Creator as in you pictures is an Infinion product.
If you have any recommendations on where to start / dev kit etc, please share.
Best regards
X
@dana, interesting, I will look into it.
@KLAUS, I looked at digital potentiometers earlier today but I could not see a continuous o or highbresolation one. They mostly havec 32 to 64 steps and only spme have 256 steps. It was not enough to get the offset close enough to 0 to still have signal...
This started with using piezo sensors but failed when it was apparent that piezo only outputs pulses and not a continuous signal. So now we have strain gauge sensors that CAN supply a continous signal as long as pressure is applied.
That is the main reason that AC coupling is not an option here...
Hello Tony,
Thank you very much for the details. That is a very good analysis and you understood my mental problem exactly.
The test you did with the DAC to test for noise is also quite clever.
Best regards
X
In this diagram, all decoupling caps after the VA supply got to AGND, which is what I thought it should be but in the schematic I asked about, also in (this datasheet somewhere), the decoupl ing capacitors after the VA to DGND instead. That is why I asked.
Hi Klaus, group,
My biggest problem in this design is space. there are 5 sensors cramped into a space of less than 50mm diameter and PCB can only have components on one side. Using this ADC in QFN + external oscillator + peripheral components (0402) already takes most of the space and I also...
Yes, ideally I need amplifiers with a gain of 1000 or even 1500.
However, they have given the bridge offset/imbalance manufacturing tolerance for this sensor +/-200mV (@3V power) which makes DC signal amplification impossible without more complex external circuitry to remove this initial bias...
Ohh I see,
You mean that the analog section only starts AFTER the 10Ohm series resistor. In that case, it would make sense to decouple only from there onwards to AGND.
regarding this ADC MCP3913...
I do not like that chip particularly, given the Errata. However, it seems the only reasonably...
I did not want to cloud the question with a lot of unnecessary information as my question is regarding grounding.
Perhaps I should have chosen a different heading but I could not think of a better one at the time and now it cannot be edited.
The question I have is purely regarding analog /...
Hello,
I am just designing the power circuit for a 24bit ADC chip interfacing to a microcontroller on the same PCB.
The manufacturer recommends separate regulators for the digital and analogue side. Fair enough.
But I am confused about the grounding configuration.
I thought the output caps of...
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