Nokia 616 Service Manual page 198

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TF5 Technical Information Nokia Customer Care
The VBIAS regulator generates a 2V.5-signal output, which is determined by the resistor
net R217/R218. This voltage is used in the HFMIC amplifier.
HF-Mute Level shifter
Figure 23: HF-Mute Level shifter
The HF-Mute level shifter transfers the 1.8V signal of the phone engine to the 10V level,
which is used by the HF-Power amplifier HFSKR.
Headset Microphone HDMIC
The microphone signal of the HD-Microphone is directly linked from the connector and
filters to the B2BHDMIC lines. The Filters can be seen in the connector block.
Headset Speaker Amplifier HDSKR
The headset speaker amplifier is realized by using N202 Boomer amplifier that is supplied
by VEBPWR. The Symmetric output of the phone engine transferred in asymmetric signal
by N200 and amplified to symmetric output signal within N202. The Amplifier can be
muted by setting HDMUTE to high This signal comes from the HDMUTE level shifter.
From
B2BXEAR
Figure 24: HD-Power amplifier realization
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Page 8a-26 Issue 2.0 Mar/2005
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