u-blox SARA-G3 Series, System Integration Manual

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SARA-G3 series - System Integration Manual
UBX-13000995 - R06 Objective Specification Design-in
Page 141 of 218
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Mount a 27 pF bypass capacitor (e.g. Murata GRM1555C1H270J) from each microphone
line to solid ground plane (C4 and C5 capacitors in
Figure 57Figure 57 ).
 Use a microphone designed for GSM applications, which typically has an internal built-in bypass
capacitor.

Connect the SPK_P and SPK_N analog downlink outputs directly to the receiver / speaker (which
resistance rating must be greater than 14  ).
 Provide proper parts on each line connected to the receiver / speaker as noise and EMI improvments,
to minimize RF coupling, according to EMC requirements of the custom application.
o
Mount a 27 pF bypass capacitor (e.g. Murata GRM1555C1H270J) from each speaker line to
solid ground plane (C6 and C7 capacitors in
Figure 57Figure 57 ).
 Provide additional ESD protection (e.g. EPCOS CA05P4S14THSG varistor array) if the analog audio
lines will be externally accessible on the application device, according to EMC/ESD requirements of the
custom application. Mount the protection close to an accessible point of the line (D1 and D2 in
Figure 57Figure 57 ).
SARA-G350
49 M IC_P
R1
R2 R4
44
SPK_P
48 M IC_N
45
SPK_N
R3
C1
46
M IC_BIAS
47 M IC_GND
C2
C3
D2
D1
C6 C7
L2
L1
C5 C4
SPK Speaker
Connector
J2
Microphone
Connector MIC
J1
Figure 57: Analog audio interface headset and handset mode application circuit
Reference Description Part Number – Manufacturer
C1 10 µF Capacitor Ceramic X5R 0603 20% 6.3 V GRM188R60J106ME47 – Murata
C2, C3 100 nF Capacitor Ceramic X7R 0402 10% 16 V GRM155R71C104KA88 – Murata
C4, C5, C6, C7 27 pF Capacitor Ceramic C0G 0402 5% 25 V GRM1555C1H270JA01 – Murata
D1, D2 Low Capacitance ESD Protection USB0002RP or USB0002DP – AVX
J1 Microphone Connector Various Manufacturers
J2 Speaker Connector Various Manufacturers
Formatted: English (U.S.)
Formatted: English (U.S.)