Microphone; Main Speaker - LG KG245 Service Manual

3. TECHNICAL BRIEF

3.10 Microphone

The microphone is placed to the front cover and contacted to main PCB. The audio signal is passed to AIN1P
and AIN1N pins of AD6537B. The voltage supply VMIC is output from AD6537B, and is a biased voltage for
the AIN1P. The AIN1P and AIN1N signals are then A/D converted by the voiceband ADC part of
AD6537B.The digitized speech (PCM 8KHz ,16KHz) is then passed to the DSP section of AD6527 for
processing (coding, interleaving etc).
VINNORP
VINNORN
Figure 3-25. Connection between Microphone and AD6537B

3.11 Main Speaker

In the case of G692 , there are 3 different speakers. One is main speaker for the received voice, another are
loud speaker for playback of ring tone , key tone and other MIDI sounds and the other is headset speaker.
The main speaker is driven directly from AD6537B AOUT1P and AOUT1N pins and the gain is controlled by
the PGA in an AD6537B. The receiver is placed in the folder cover and connected to AOUT1x terminal via
FPCB.
2V5_VMIC
R202
1K
R206
2.2K
R210 100
C211
39p
C215 0.1u
R217 100
R221
2.2K
CLOSE TO MIC
- 42 -
C208 C204
10u
39p
C212
39p
(BSE, -42dB, FPCB Type)
C217 C218
39p 39p
MIC