LG U990 Service Manual page 66

3.10.7.1 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 (MSM6280).
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 (MSM6280) 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.
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
Figure. Audio Interface Detailed Diagram(MSM6280)
3. TECHNICAL BRIEF
- 67 -
LGE Internal Use Only