Combining analog and digital ground

[mikl604]

Have a nice day!
Tell me about the wiring of the earthen tire for ESP 32-WROOM-32D. I use the ADC on pins 5 and 6. To reduce interference, I do not use pins 4 and 7, assigned them as inputs and put them on the ground, resulting in an earthen barrier around the ADC inputs. I know that the analog and digital earth should be combined at 1 point. But the ESP 32 has several ground pins. Which is the best way to get an analog ground so that there is as little interference as possible?

[selcuk]

Generally, if you don't have a specific purpose, you can connect both analog and digital grounds to the same ground plane. The noise is coupled through a common impedance. The purpose here is to reduce the impedance and so the noise. Impedance is mainly resistive for low frequency and mainly inductive for high frequency. So using a solid ground plane is a good idea. It will prevent signal return path discontinuties (split planes) as well.

https://link.springer.com/chapter/10.10 ... 14186-7_14
https://link.springer.com/chapter/10.10 ... 14186-7_16

ESP32 chip has one ground pin (central pad) by the way.