Nokia Customer Care TF5 Technical Information
Company Confidential TFE-4/RV-1
Issue 2.0 Mar/2005 Copyright © 2005 Nokia Corporation. Page 8a-25
Company Confidential
Figure 20: Realization of HFMIC (Part 2)
In the second part the single-sided signal is transferred to symmetric output, which is
used by the phone engine.
Handsfree-Speaker (HFSKR)
Figure 21: Handsfree Speaker Amplifier Realization
The symmetric signal comes from the prefilter and reaches the symmetric power ampli-
fier. With the HFMute signal coming from the HF-Mute Level-Shifter, the amplifier can
be switched on (HSMUTE<1.5 V) or off (HSMUTE = >3.5V).
VBIAS Regulator
Figure 22: VBIAS Regulator
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