LG CU920 Manual page 73

3.10.9 Audio Signal Processing & Interface
Audio signal processing is divided uplink path and downlink path.
The uplink path amplifies the audio signal from MIC and converts this analog signal to digital signal
and then transmits it to DBB Chip (MSM6281).
This transmitted signal is reformed to fit in GSM & WCDMA frame format and delivered to RF Chipset.
The downlink path amplifies the signal from DBB chip (MSM6281) and outputs it to receiver (or
speaker). The receive path can be directed to either one of two earphone amplifiers or the auxiliary
output. The outputs earphone1 (EAR1OP, EAR1ON) and auxiliary out (LINE_OP, LINE_ON) are
differential outputs. Earphone2 (HPH_L, HPH_R) is a single-ended output stage designed to drive a
headset speaker. The microphone interface consists of two differential microphone inputs, one
differential auxiliary input and a two-stage audio amplifier.
CODEC
Cod ec Tx
Microphone
MIC1P
MIC_AMP2
MIC_AMP1
MIC1N
0dB or
-6dB to +25.5dB
+24dB
1.5dB steps
MIC2P
MIC2N
AUXIP
Mux
AUXIN
Line_L_IP MIC_AMP2
MIC_AMP1
0dB
-6dB to +25.5dB
Line_L_IN
+24dB
1.5dB steps
Line_R_IP
Line_R_IN
Earphone
70mW max.*
EAR1OP
+
- -
EAR1ON
+
21.6 mW max.*
HS/
HPH_L -
Mux
+
+
Sum
Capless Driver
Out
-
+
HPH_R
0.58 mW max.*
AUX_OUT -
+
2.30 mW max.*
AUXOP / Line_L
+
Code c Rx
AUXON / Line_R - -
+
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
Audi o DSP
HPF &
SLOPE
TX_HPF_DIS_N
A/D
CODEC_TX_GAIN
TX_SLOPE_FILT_DIS_N
HPF &
SLOPE
CODEC_TX_GAIN
TX_HPF_DIS_N
A/D
TX_SLOPE_FILT_DIS_N
CODEC_ST_GAIN
RX_HPF_DIS_N
CODEC_RX_GAIN
D/A
X HPF
D/A
RX_HPF_DIS_N
CODEC_RX_GAIN
X HPF
Figure. Audio Interface Detailed Diagram(MSM6281)
3. TECHNICAL BRIEF
PCM Interface
Right Data Out
X
nsSwitch
NS &
PCM
AAGC
Left Data Out
IF
X
ESEC DTMF
or Detection
AEC
X
+ Left Data In
PCM
IF
RX_VOLUME
ecSwitch
ecMode
++ Refer to Loopback Test
Command
Right Data In
Au di o DSP
- 75 -
TxPcmFilt TX_VOLUME PACKET
Enc oder
LOOPBACK
Tx FIR X
HR/FR/EFR
13K CELP
DTMF_TX_GAIN
AMR
Encoder
X
DTMF NES
Generation
(DFM
only)
AUDIO
X
++
LOOPBACK
HR/FR/EFR
13K CELP
DTMF_RX_GAIN
AMR
Decoder
X AAGC
Rx FIR
RxPcmFilt
Decode r
** Gain = 20LOG(Value/16384)
Range is -84dB to +12dB
LGE Internal Use Only
++