Analgo ground vs normal ground

[chris007]

Is there any real different between an analog ground for audio signal for example and normal ground for all other circuit ?
If yes, how do you organize your PCB layout and design to take in consideration that those two different ground are not same but also the same ?

[mairomaster]

Rober posted this link some tome ago, you can take a look:

https://www.maximintegrated.com/en/app-notes/index.mvp/id/5450

It is a very big topic and there are many useful resources on the web. The basic idea is that you need to keep your analogue ground as clean as possible (noise free). It is often separated from the digital ground in the circuit, since the digital ground is noisy (it is not a perfect ground - the voltage of it fluctuates around 0 volts which is practically noise).

[robertferanec]

chris007 this is a big topic. In the boards which we design (CPU boards) we do use audio and I do not separate the grounds - we just use one common ground for the whole board. I try to place audio into a "quite" corner (away from the possible path of high and noisy currents), I place all the analog components on one side PCB only (in the "quite" corner I do not mix analog & digital components) and I do not mix the analog tracks with digital tracks (in the "quite" corner I use specific layers for analog signals only). This works oki.

However, the way how to combine digital and analog circuits may be very individual between boards and you may want to follow design guide recommended by the analog chip manufacturer or in some other cases you may want to split the grounds .... there is no universal answer.