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3. TECHNICAL BRIEF
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3.11.8.1. 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
(MSM6245). 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 (MSM6245) 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_P, LINE_N) 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.
(+16.5dB)
Figure 1.24 Audio Interface Detailed Diagram(MSM6245)