TFE-4/RV-1 Company Confidential
TF5 Technical Information Nokia Customer Care
Page 8a-24 Copyright © 2005 Nokia Corporation. Issue 2.0 Mar/2005
Company Confidential
Description of the HW Realization
Handsfree Microphone (HFMIC)
Figure 19: Realization of HFMIC (Part 1)
In Figure 19, the realization of the first part of the HFMIC Block is shown. The micro-
phone is connected to an SMK connector. Afterwards there is some ESR filtering and a
Bias voltage is applied to the microphone. In the next stage the signal is multiplied by
the amplifier N200. To set Bias level at the positive input of this amplifier the voltage
2Vbias is used.
HDEAR_P
HDEAR_N
Symmetric Audio Signal gen-
erated by Headset Speaker
Amplifier
No Audio Signal to Head-
set-Speaker
HFSPKR Single-ended Audio Signal
generated by handsfree
Speaker Amplifier
No Audio Signal to
Handsfree-Speaker
HFMIC Single-ended Audio Signal
generated by Handsfree
Microphone. Gets VMIC as
Phantom voltage
No Microphone Signal
from Handsfree
Signalname Description Range When Error then .......
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