LG KE990 Service Manual - Page 55

Audio Signal Processing & Interface

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3. TECHNICAL BRIEF 3.9.7.1 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 (ESM6270). 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 (ESM6270) 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. Figure. Audio Interface Detailed Diagram(ESM6270) LGE Internal Use Only - 56 - Copyright © 2008 LG Electronics. Inc. All right reserved. Only for training and service purposes

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LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc.
All right reserved.
Only for training and service purposes
3.9.7.1 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 (ESM6270).
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 (ESM6270) 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.
3. TECHNICAL BRIEF
- 56 -
Figure. Audio Interface Detailed Diagram(ESM6270)