We sample an Analog signal using AD7367 and then reconstruct it using AD5554. It is done almost simultaneously for 2 or 4 channels and we checked and there is no cross-talking between the channels.
We test 1 channel at teh time and the same problems appears in all of them:
When we sample at 41 Khz. we see a strange bump in the spectrum at
When we sample at 65 KHz, this bump moves to around 19 KHz. See attached graphs for details.
We input the signal before the ADC and measure after the first amplifier on the DAC (see orange circle on schematics).
We got the same project with 1 channel using AD7457 ADC and AD5620 voltage DAC sampled at 90 KHz. and we don't see any bumps like that.
We also sample there without a filter immediately after the DAC
Could you please tell me what is the problem and how can we fix it?
We don't have such a sharp low-pass filter to remove this bump .
Could you specify the name and scale of the X and Y axes, please?
Miss the excel sheet.
Y is ratio between input to output or amplitude (it doesn't matter because the peak is relative and absolute).
X axis is frequency in KHz.
I attach my Excel file
There is one corrupted graph because of a bad contact in the probe. Please disregard it.
I sent again but your computer/firewall probably blocked it.
It is not necessary for understanding the problem. Did you receive my E-mail with 5 attachments?
What is the ADC SPS?
And the update rate of the DAC?
Your result is similar to a Sinc filter.