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3. TECHNICAL BRIEF
3.9 Microphone
The microphone is placed to the Front cover and contacted to main PCB. The audio signal is passed
to MIC_N and MIC_N 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).
LGE Internal Use Only
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
Figure 3.9 Connection between Microphone and AD6721
CLOSE TO MIC
100K
100ohm
C207
R223
10
VCC
1
U202
NLAS5223BMNR2G
3
COM1
9
COM2
6
GND
IN1
4
IN2
8
5
NC1
NC2
7
NO1
2
NO2
C224
39p
0.1u
C217
39p
C209
2.2K
R218
10u
C205
2V8_VEXT
2V5_VMIC
1u
C206
39p
C213
VA204
ICVN0505X150FR
1
2
OB4-15L42-C33L
MIC200
39p
C212
C225
VA203
ICVN0505X150FR
39p
R225
2.2K
R222
100ohm
R214
1K
MIC_N
MIC_P
MULTI_MIC_N
MULTI_MIC_P
VINNORN
VINNORP
MIC_PATH_SEL
MIC_PATH_SEL
MIC_N
MIC_P
Содержание MG295
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