Baseband Electrical Interfaces: Audio Components; Baseband Electrical Interfaces: Backlight And Illumination - Nokia RM-761 Service Manual

RM-761; RM-799; RM-800
System Module

Baseband electrical interfaces: Audio components

DC blocking capacitors C2102 are inserted to center the audio input around the internal bias level. The
microphone circuit is configured in pseudo-differential mode. VMIC is used for the bias. A low-pass filter
comprising R2100 and C2101 is used to remove any potential noise picked-up by VMIC.
The external microphone for the headset is connected via filtering components to the second differential
microphone input MICP2 and MICN2, and is designed pseudo-differentially for better noise immunity. DC
blocking capacitors C2107 are used. VUMIC for the biasing. A low-pass filter comprising R2105 and C2105
removes any potential noise picked-up by VUMIC.
Figure 63 Earpiece and loudspeaker components

Baseband electrical interfaces: Backlight and illumination

The backlight supply is implemented using the integrated boost converter control circuit of X-Gold213.
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