Audio Interface - LG 410G Service Manual

3. H/W Circuit Description

3.10 Audio Interface

3.10.1 Uplink Path
A voice signal is converted to electrical signal with Microphone. The converted electrical voice signal is
amplified and converted to digital signal in ABB(T3031). The converted digital data is encoded to GSM
voice standard in DBB(LOCOSTO).
The audio signals from main microphone goes to MICP and MICN of ABB and the voice signal from
head-set to HSMIC of ABB. The bias voltage for microphone is 2V for main mic. and 1.8V for head-set
mic,
which bias voltage is generated in ABB(MICBIAS, V_IO)
L200
MICIP
100nH
C223
DNI
C224
MICIN
3.10.2 Downlink Path
The voice downlink path receives speech samples at the rate of 8 kHz/16kHz from the DSP via the
voice serial interface VSP and converts them to analog signals to drive the external transducers.
LGE Internal Use Only
MICBIAS
R214
1K
C220 C221
0.1u 10u
C222 22n
22n
Figure 3-10-1 Main Mic interface
-24-
R225
VA205
DNI
C217
39p
R227 0
C225
DNI
- 28 - Copyright © 2009 LG Electronics. Inc. All right reserved.
L201
100nH
MIC200
1
OUT
2
G1
3
G2
4
G3
5
PWR
6
G4
SPM0204LE5-QB
Only for training and service purposes