Pi Zero W and Pi3 3v3 ripple when wifi busy

[yodakohl]

I'm using the raspberry's 3v3 voltage to supply two digital mems microphones.
This is working fine for the original Pi Zero. However when using a Pi Zero W
or a Pi3 I'm getting some serious noise, but only when the Wi-Fi is transmitting data.
Here are captures of the 3v3 voltage measured from the raspberry 3v3 pin.






The two microphones are pulling a maximum current of 1.2 mA and can also be supplied as with 1.8V.
Do you have any suggestions how to get a cleaner supply for the microphones? I was thinking of some ways to do it:

• Use a separate low noise regulator from 5v to 3v3 or from 3v3 to 1v8
• Using ferrite beads
• Decoupling Capacitors (currently 0.1u and 200p)

Any help is appreciated.

[TJ232]

Just few days ago moved from PI2 to the new fresh PI3 and found the same problem for some external hi-res ADC's and DAC's extension board. Using a MCP1700 LDO for providing the necessary 3.3V for them solved the problem. But for another one, at full 24 bit, was forced to use a MIC94310. That noise is quite annoying.

[yodakohl]

Thanks, just got my MIC94310 and they are working great