EVAL_AD4080ARDZ sine wave positive_half is noisy(distorted)

Hi,

         Can you please show the input signal, with Vpp information and the DC offset for each input, I would first probe them at the IN+ and IN- test points, then at the  ADC_IN_P, and ADC_IN_N points, (by just probing at R32 and R33).  At R32 and R33 you should see each input should be offset by 1.5VDC. It was not necessary to populate R30, as the ADA4945 will already be setting the VCM at 1.5V, derived from the voltage at FDA_CLAMP_P (connected to VREF at 3V) and FDA_CLAMP_N (connected to AGND) these are connected with already populated 0 Ohm resistor links at RJ5 and RJ6.

        It is good to probe the signal at these points to check the voltage is correct, however I would remove these when acquiring data, as the probe could compromise the performance.

The output in ACE looks very distorted in both the positive and the negative parts of the sine wave.  What is the signal source that is being used here? 

Are there any additional probe being placed on the digital signals that could be causing data integrity issues?.

   Rgds,

    Ds

Dear Mr Ds

Thank you very much for your prompt reply so quickly!

I will send you the following as separate .PNG files:

* Measurement Setup

* Waveforms of IN_P and IN_N, waveforms of R32 and R33, and ADC output at 2Vpp (IN_P=1Vpp, IN_N=1Vpp (inverted)) at  10kHz sinwave

* ADC output at 2kHz sinwave

I used a Tektro DPO2024B 200MHz oscilloscope.

I used an easy-to-use ADALM2000 as signal generator.

(Unfortunately, I do not have expensive signal generators in my lab.)

The oscilloscope's GND probe uses the included leads, so the bright line is slightly thick, but

It can be seen that INP and INN are offset = 0V, and R32 and R33 are operating relative to 1.5V.

Since the input and output waveforms are completely different, I don't think it's an analog input issue.

I'm concerned it might be my mistake with ACE setting(**), or perhaps the evaluation board is broken...

(**)AD4080 initial configulation in the ACE setup is as same as default, I changed nothing from default.

Any comments or advice would be greatly appreciated.

Thank you for yoour support.

Best Regards

Setup

10kHz sin 2Vpp

2KHz sin 2Vpp

Best Regards

Hello

Please let me add further information below.

EVAL_AD4080ARDZ:  Ver 1.2026.421203.

Thank you for your support.

Hi,

      Thanks for this update, the input signal looks reasonable and as expected, so it does look like something more on the interface side of things that is the issue. The ACE version is the latest version and correct.

    Can I ask, when you start ACE, connect to the board and begin acquiring data, that you have not modified any other registers etc. in the device memory map or modified any other settings? 

      The pattern of the data looks unusual, it could be worth zooming in to the data to look at 50- 100 samples only to see if there is some pattern to it. (It seems to be roughly the correct shape for a sine wave, with corrupt results going to ~6 other discrete levels, e.g. code 0 , close to code 20000 etc.

    Another thing that would be interesting to know is if the SDP-K1 you are using has been used with other boards, or if there is a way to check there is no issue with that.

     Thanks,

          Dom

Dear Dom-san,

Thank you for your quick answer.

I had install AD4080 plug-in again for each power up, then I think I can see correct waveform .

I was sorry to bother you , but thank you for your cooperation.

Thank you

Best Regards

No problem, glad we could help.