Multiple ADC sample with different frequency interference?

[pxueh.1]

Hi,everyone.I'm use NUCLEO-L496ZG platform.

ADC1 sample at a frequency of 5M,ADC3 sample at a frequency of 12.8K(PWM trigger).

when only run ADC3,ADC3's waveform is normal.

when ADC1 and ADC3 run at the same time,ADC3's waveform has a lot of interference.How to solve this problem? if had recommend frequency of ADC1 when ADC3 sample at a frequency of 12.8K? ADC1's frequency nend greater than 2M.

Time-domain waveform of ADC3(only ADC3 sample)

 

Time-domain waveform of ADC3(ADC3 and ADC1 sample together) 

Frequency spectrum waveform of ADC3(ADC3 and ADC1 sample together).

The follow picture is Enlarged view.(ADC3 and ADC1 sample together)

Input signal.

Interference signal. The same of other three. Interval of frequency is 2560Hz

[TDK]

What is the frequency of the interference? Looks super regular, might shed some light. Y seems to be counts, but what is the X axis?

[pxueh.1]

Y is Amplitude, X is time.

[pxueh.1]

@TDK (Community Member) Thank you for your response. The picture is Time-domain waveform. Y axis value read from ADC3 regular data register (ADC_DR), X axis is counts.

[pxueh.1]

Thank you for your response. The picture is Time-domain waveform. Y axis value read from ADC3 regular data register (ADC_DR), X axis is counts.