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3. TECHNICAL BRIEF
3.8 Microphone
The microphone is placed to the Front cover and contacted to main PCB. The audio signal is passed
to MIC_N and MIC_P pins of AD6721.
The voltage supply VMIC is output from AD6721, and is a biased voltage for the MIC_P. The MIC_P
and MIC_N signals are then A/D converted by the voice band ADC part of AD6721.
The digitized speech (PCM 8KHz ,16KHz) is then passed to the DSP section of AD6721 for
processing (coding, interleaving etc).
[Rev.C] Exchange Mic. Polarity
VINNORP
VINNORN
Figure 3.8 Connection between Microphone and AD6721
LGE Internal Use Only
2V5_VMIC
R227
1K
R230
C212
39p
2.2K
R231
100ohm
C231
39p
C232
R235
0.1u
100ohm
R239
2.2K
- 36 -
C211
10u
MIC200
C213
1
2
39p
OB4-15L42-C33L
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
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