3. TECHNICAL BRIEF
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Only for training and service purposes
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3.12 Audio Front-End
3.12.1 General Description
3.13.2 Functional Specifications
See the table below for the functional specifications of voice-band uplink/downlink blocks
Figure 3.12.1. Block diagram of audio mixed-signal blocks.
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Only for training and service purposes
LGE Internal Use Only
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Figure 3.12.1. Block diagram of audio mixed-signal blocks.
3.12.1 General Description
Audio mixed-signal blocks (AMB) integrate complete voice uplink/downlink and audio playback function. As
shown in the figure below, it includes three parts. The first consists of stereo audio DACs and audio amplifiers
for audio playback. The second part is the voice downlink path, including voice-band DACs (left channel
audio DAC) and voice amplifier, which produces voice signal to earphone or other auxiliary output device.
Amplifiers in the two blocks are equipped with multiplexers to accept signals from internal audio/voice. The
last part is the voice path, which is the interface between the microphone (or other auxiliary input device)
input and MT6255 DSP. A set of bias voltage is provided for the external electric microphone.
3. TECHNICAL BRIEF
3.12 Audio Front-End
48
3.13.2 Functional Specifications
See the table below for the functional specifications of voice-band uplink/downlink blocks.
Voice or Audio
Digital Signal
Voice or Audio
Digital Signal
Voice Signal
Voice
ADC
M
U
X
M
U
X
PGA
LSB
HS_AMP
HPR_AMP
HPL_AMP
Class_AB
1.2V
AU_V1N1_P
AU_V1N1_N
AU_V1N0_N
AU_V1N0_P
SPK_N
SPK_P
AU_HPL
AU_HPR
AU_HSM
AU_HSP
MICBIAS1(1.9V)
MICBIAS0(1.9V)
Audio
LCH-DAC
Audio
RCH-DAC
Digital MIC
I/O Signal