I tried decoupling Vcc as recommended in AN2519 : Figure 2-2
my PCB is as recommended in appnote, MCU is decoupled from Vcc using ferrite bead and 100nF cap close to MCU
I never used ferrite beads before and dont know how to calculate right value of ferrite bead for my PCB
I did 5 trial with different parts (all 1206 footprint) placing between reg and MCU
1) Ferrite bead 1k/100MHz
2) Ferrite bead 600R/100MHz
3) Ferrite bead 120R/100MHz
4) Inductor 10uH
5) Resistor 10R
as I understand from appnote the aim of ferrite bead is to prevent spread noise from MCU to other devices
but it seems using ferrite beads - in my trials - causes increase ripples on MCU side
without ferrite bead/Inductor there is no ripples on MCU side
is it normal to have some ripple in MCU side for the sake of not affecting other devices by MCU ?
I attached schematic and test results
I appreciate anyone sharing experiences