I am working with a FRDM-KL25Z board, and I am having problems with the noise when the ADC starts working.
I am analizing a 25KHz signal that is amplified and then is measured by the ADC (pin PTB0/ADC0_SE8). I make several measurements as fast as possible in order to detect the maximum of the signal.
Please find below a picture of the signal in the PTB0 pin when no ADC conversions are taken.
And now, please find below the same signal in the same pin when ADC conversions are being performed.
I placed 1nF capacitor in the PTB0 pin but the the noise is still there.
Could anybody help?
Thank you very much in advance.