WM_PRJ_Q2400_PTS_005 -007
18th January 2006
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B/ Single-ended connection
Typical implementation:
L1
C1
C2
MIC1P
MIC1N
V
AUDIO
C4
R1
R2
L2
C3
C5
Figure 15: MIC1 inputs (single-ended connection)
Note:
VAUDIO must be very “clean” in single-ended connection (for example, VCC
plus filter cell like RC or LC).
R1 = from 100 Ω to 330 Ω.
R2 = usually between 1 kΩ and 3.3 kΩ as per the V
AUDIO voltage level and the
microphone characteristics.
C1 = 10 pF to 33 pF.
C2 = C3 = C5 = 47 pF to 100 pF.
C4 = 47 µF.
L1 = L2 = 100 nH.
R1 is used as a voltage supply filter with C4.
C5 has to be the nearest possible to the microphone. Microphone manufacturers
provide this capacitor directly soldered on the microphone.
C1, C2, C3 have to be very close to the WISMO module connector.
L1, and L2 has to be put near the WISMO module 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.
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