User's Manual

UE910 3G HARDWARE USER GUIDE 1vv0301171 Rev.3 • 2015-04-17 58 of 78

MIC connection

The bias for the microphone has to be as clean as possible; the first connection (single ended) is

preferable since the Vmic noise and ground noise are fed into the input as common mode and then

rejected. This sounds strange; usually the connection to use in order to reject the common mode is the

balanced one. In this situation we have to recall that the microphone is a sound to current transducer,

so the resistor is the current to tension transducer, so finally the resistor feeds the input in balanced

way even if the configuration, from a microphone point of view, seems to be un-balanced.

The following images show some connection examples: