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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 VINNORP and VINNORN pins of AD6724. The voltage supply VMIC is output from AD6724, and is
a biased voltage for the VINNORP. The VINNORP and VINNORN signals are then A/D
converted by the voice band ADC part of AD6724.The digitized speech (PCM 8KHz ,16KHz) is then
passed to the DSP section of AD6724 for processing (coding, interleaving etc).
MAIN MIC
R227
VINNORP
100ohm
C230
39p
R228
VINNORN
100ohm
Figure 3.8 Connection between Microphone and AD6724
LGE Internal Use Only
2V5_VMIC
R221
1K
R226
C227
C229
2.2K
10u
39p
C231
39p
C232
0.1u
R229
VA202
C233
C234
2.2K
39p
39p
- 32 -
MIC200
2
SUMY0003802|mic_ob4_15l42_c33_bottomview
1
OB4-15L42-C33L
VA203
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
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