Q2406 Datasheet, PDF (30/81 Pages) List of Unclassifed Manufacturers – SELF CONTAINED E GSM/GPRS 900/1800 OR 850/1900 BI BAND MODULE

WM_PRJ_Q2400_PTS_002 - 002
24th January 2003
2.12.1.2 Main Microphone Inputs (MIC2)
The MIC2 inputs are differential ones. They already include the convenient
biasing for an electret microphone (0,5 mA and 2 Volts). This electret
microphone can be directly connected on these inputs. The impedance of the
microphone 2 has to be around 2kΩ. These inputs are standard ones for an
handset design while MIC1 inputs can be connected to an external headset or
a handsfree kit.
AC coupling is already embedded in the module.
Typical implementation:
L1
C1
L2
C3
MIC2P
C2
MIC2N
C4
Figure 3 : MIC2 inputs (differential connection)
C1 = 10pF to 33pF
C2 = C3 = C4 = 47pF to 100pF
L1 = L2 = 100nH
C1 has to be the nearest possible to the microphone. Microphone
manufacturers provide this capacitor directly soldered on the microphone.
C2 has to be very close to the WISMO Quik Q24x6 Series connector.
L1, L2, C3 and C4 has to be put near the WISMO Quik Q24x6 Series connector
and can be removed according to their environment (ground plane, shielding,
etc…). The best way is to plan all the components and to remove those which
are not necessary to filter out the TDMA noise on the audio path.
Pin description
Signal Pin # I/O
MIC2P
46
I
MIC2N
48
I
I/O type
Analog
Analog
Description
Microphone 2 positive
input
Microphone 2 negative
input
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