> 4.9.1 | Power Supply Related Audio Problems

> Audio problems may occur due to insufficient power supply filtering and different GND levels between PCBs.
> The example in Figure 25 shows the problem of ground bouncing which, in principle, can affect speaker and microphone path:
> Figure 25: Ground bouncing problem (example)
> The example assumes the following scenario:

> • | Typical peak power consumption is 2A.

> • | Typical connector resistance is 5…20mOhms.

> In the example the speaker connected from EP to GND would have an SNR of only 12dB! This problem can be resolved by

> • | a balanced usage of outputs or

> • | by connecting the unbalanced speaker to AGND of the GSM module (see [1]).

> For more information refer to Section 4.6.