LG CU920 - Page 73

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3. TECHNICAL BRIEF
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.
LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
E
arphone
Micr
ophone
MIC1P
MIC1N
MIC2P
MIC2N
EAR1ON
EAR1OP
HS/
HPH_L
AUXON / Line_R
-
+
+
--
+
70mW max.*
21.6 mW max.*
Codec Rx
Codec Tx
A/D
-
+
HPH_R
D/A
D/A
AUXOP / Line_L
+
--
+
2.30 mW max.*
Mux
+
Sum
Out
HPF &
SLOPE
X
CODEC_TX_GAIN
TX_HPF_DIS_N
TX_SLOPE_FILT_DIS_N
CODEC_ST_GAIN
X
HPF
RX_HPF_DIS_N
Right Da
ta In
+
Left Data In
PCM Interface
PCM_LOOPBACK
CODEC
Audi o DS
P
Line_L_IP
AUXIP
AUXIN
Mux
HPF &
SLOP
E
A/D
X
CODEC_RX_GAIN
HPF
RX
_HPF_DIS
_N
X
CODEC_RX_GAIN
0dB
or
+24dB
MIC_AMP1
X
CODEC_TX_GAIN
MIC_AMP2
-6dB to +25.5dB
1.5dB st
eps
0dB
+24dB
MIC_AMP
1
MIC_AMP2
-6dB to +25.5dB
1.5dB st
eps
Left Data Out
Right Data Out
TX_HPF_DIS_N
TX_SLOPE_FILT_DIS_N
Line_R_IP
Line_L_IN
Line_R_IN
0.58 mW max.*
-
+
AUX_OUT
Capless Driver
PCM
IF
PCM
IF
X
HR/FR/EFR
13K CELP
AMR
En
coder
TX_VOLUME
RX_VOLUME
nsSwitch
TxPcmFilt
RxPcmFilt
ecSwitch
ecMo
de
DTMF
Generation
DTMF
Detection
DTMF_RX_GAIN
DTMF_TX_GAIN
ESEC
or
AE
C
Encoder
Decoder
13K CELP
AMR
Deco
der
Tx FIR
NES
(DFM
only
)
AAGC
AUDIO
LOOPBACK
++
PACKET
LOOPBACK
++
** Gain = 20LOG(Value/16384)
Range is -84dB to +12dB
++ Refer to Loopback Test
Command
Audi o DSP
NS &
AAGC
X
X
X
Rx FIR
HR/FR/EFR
Figure. Audio Interface Detailed Diagram(MSM6281)