Creating an RF-Filter for GSM2 Microphone ?

Official Hardware Retired GSM Shield
1

Hello,

It's due reducing Noise during Communication.

In this Datasheet
you may find on Page 51, the Microphone Scheme.
May someone explain what is an ESD-Anti Component ?

Thanks

2

Hello,

I found out that the ESD-Anti Component, is a Diode for Electro Static Discharge Protection.

I couldn't find the same as in the Datasheet, but similar and only SMD install.

With a bit struggle I could it solder together, and it's to test.

3

Hi,

I tested the Module, but no sound from the Microphone.

I checked the Connections (Datasheet on Page 51) and looks like okay. But I don't know if the ESD diodes works, perhaps I have to change it with a non-smd.

What is a Differential Layout, as in the Datasheet ?

I tested also only with an Electret Microphone, without RF-Filter Module, and it makes Noise.

Perhaps somebody have created such a Module, or have similar Problems ?

Or may someone advise, which kind of Microphone to use ?

Edit 1 - I used a bread board to replicate that module, but it has still no sound. (seems not be a differential Layout or Anti-ESD Problem ?)

Thanks a lot
Qbit