Part Number:TMS320F28035
The ADC of the microcontroller has two seperate sample and hold capacitors to hold input voltages from group A inputs and group B inputs.
On our PCB, we can measure significantly more noise on group A inputs, compared to group B inputs (noise at 320MHz). We expect that the noise is introduced by a partial power plane, which isn't shielded from the ADC for group A as well as for group B (see image of the ground plane between the chip on top plane and partial power plane).
Could you please confirm, that the S/H capacitor of group A is shielded worse than the one of group B? I do not know the location of those capacitors on the die, that's why I'm asking.
Best Regards
Tino Gfrörer