LG CG225 Service Manual page 28

3.5.2. Audio Signal Processing & Interface
The voice codec circuitry processes analog audio components in the voice uplink (VUL) path and
applies this signal to the voice signal interface for eventual baseband modulation. In the voice
downlink (VDL) path, the codec circuitry changes voice component data received from the voice serial
interface (VSP) into analog audio.
HSMICP
78 mV
RMS
18 dB
AUXI
4.6 dB or
365 mV
RMS
28.2 dB
Sensitivity
49.3 dBv/Pa
MICAMP
25.6 dB
32.5 mV
RMS
1.385 V
RMS
EARAMP
1 dB
Sensitivity
106.7 dBspl/Vrm
AUXAMP
692 mV
RMS
5 dB
HSOAMP
346 mV
RMS
5 dB
SLR = (8 dB
620 mV
RMS
ADC
2.48 dB
1b + 1b
VREF 1.75 V
1.237 V
RMS
4b
DAC and Digital
Smoothing Modulator
Filter 0 dB 0 dB
RLR = (2 dB
Figure 10. Audio Interface Block Diagram
- 27 -
3. H/W Circuit Description
±
3 dB)
PGA:
UL Filter Gain: 0 dB
3.25 dB 12 dB to 12 dB
1-dB Step
Sidetone:
1 dB to 23 dB
Mute
PGA
DL Filter
Gain: 0 dB
0 dB
6 dB to 6 dB
1-dB Step
±
3 dB)
3 dBm0
Full Scale
16 Bits
3 dBm0
Volume
Full Scale
Control
0 dB to 24 dB
16 Bits
+ Mute