User Guide

Figure 20 Audio block diagram
Internal microphone
Internal microphone is used for HandPortable (HP) and Internal HandsFree (IHF) call modes.
An analogue electret microphone is connected to Retu ASIC’s Mic1P and Mic1N inputs via asymmetric electrical
connection.
The microphone is biased by Retu ASIC MicB1 bias voltage output.
Figure 21 Internal microphone circuitry
External microphone
Galvanic accessories are connected to the system connector (Pop-Port
TM
).
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