UMTS/HSPA Module Series
WCDMA UGxx Audio Design Note
WCDMA_UGxx_Audio_Design_Note Confidential / Released 17 / 56
4
Design Consideration
4.1. Power Supply for PCM Codec
For different PCM codec, the supply voltage is different. It
’s better to supply power for PCM codec with
dedicated LDO, and not to share this power with other circuits.
4.2. Audio Layout
Power supply ripple, unbalanced ground and RF burst radiation have negative effect on audio layout.
Layout of MICP_PCM/MICN_PCM, SPKP_PCM/SPKN_PCM must meet the rule of differential signal.
Moreover, these two pairs of signals should be separated from each other by flooding ground to avoid
echo issue from SPK signal to MIC signal. Figure 10 shows an example.
Figure 10: Audio Layout
Quectel
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