Description Of The Hw Realization - Nokia 616 Service Manual

TFE-4/RV-1
TF5 Technical Information
Signalname
HDEAR_P Symmetric Audio Signal gen-
HDEAR_N erated by Headset Speaker
Amplifier
HFSPKR Single-ended Audio Signal
generated by handsfree
Speaker Amplifier
HFMIC Single-ended Audio Signal
generated by Handsfree
Microphone. Gets VMIC as
Phantom voltage

Description of the HW Realization

Handsfree Microphone (HFMIC)
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.
Page 8a-24
Company Confidential
Description
Figure 19: Realization of HFMIC (Part 1)
Copyright © 2005 Nokia Corporation.
Company Confidential
Nokia Customer Care
Range When Error then .......
No Audio Signal to Head-
set-Speaker
No Audio Signal to
Handsfree-Speaker
No Microphone Signal
from Handsfree
Issue 2.0 Mar/2005