Integration Manual
SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R13 Design-in Page 53 of 119
2.2.1.10 Additional guidelines for VCC supply circuit design
To reduce voltage drops, use a low impedance power source. The series resistance of the supply lines (connected to the
modules’ VCC and GND pins) on the application board and battery pack should also be considered and minimized: cabling
and routing must be as short as possible to minimize losses.
Three pins are allocated to VCC supply connection. Several pins are designated for GND connection. It is recommended
to correctly connect all of them to supply the module minimizing series resistance.
To reduce voltage ripple and noise, improving RF performance especially if the application device integrates an internal
antenna, place the following bypass capacitors near the VCC pins:
• 68 pF capacitor with Self-Resonant Frequency in the 800/900 MHz range (e.g. Murata GRM1555C1H680J), to filter
EMI in the low cellular frequency bands
• 15 pF capacitor with Self-Resonant Frequency in the 1800/1900 MHz range (as Murata GRM1555C1H150J), to filter
EMI in the high cellular frequency bands
• 10 nF capacitor (e.g. Murata GRM155R71C103K), to filter digital logic noise from clocks and data
• 100 nF capacitor (e.g. Murata GRM155R61C104K), to filter digital logic noise from clocks and data
An additional capacitor is recommended to avoid undershoot and overshoot at the start and at the end of RF
transmission:
• 100 µF low ESR capacitor (e.g Kemet T520B107M006ATE015), for SARA-R412M supporting 2G
• 10 µF capacitor (or greater), for the other SARA-R4/N4 series modules that do not support 2G
An additional series ferrite bead is recommended for additional RF noise filtering, in particular if the application device
integrates an internal antenna:
• Ferrite bead specifically designed for EMI suppression in GHz band (e.g. Murata BLM18EG221SN1), placed as close
as possible to the VCC pins of the module, implementing the circuit described in Figure 27, to filter out EMI in all the
cellular bands
C5
GND plane
VCC line
Cap acit or wit h
SRF ~9 00 MHz
C1 C3 C4
FB1
Ferr it e Bead
f or GHz noise
C2
C1
GND
C2 C4
SARA-R4/ N4
52
VCC
53
VCC
51
VCC
3V8
C5
+
FB1
C3
Capacit or wit h
SRF ~1900 MHz
SARA
Figure 27: Suggested design to reduce ripple / noise on VCC, highly recommended when using an integrated antenna
Reference Description Part Number - Manufacturer
C1 68 pF Capacitor Ceramic C0G 0402 5% 50 V GRM1555C1H680JA01 - Murata
C2 15 pF Capacitor Ceramic C0G 0402 5% 50 V GRM1555C1H150JA01 - Murata
C3 10 nF Capacitor Ceramic X7R 0402 10% 16 V GRM155R71C103KA01 - Murata
C4 100 nF Capacitor Ceramic X7R 0402 10% 16 V GRM155R71C104KA01 - Murata
C5
100 µF Capacitor Tantalum B_SIZE 20% 6.3V 15mΩ
T520B107M006ATE015 – Kemet
10 µF Capacitor Ceramic X5R 0603 20% 6.3 V GRM188R60J106ME47 - Murata
FB1 Chip Ferrite Bead EMI Filter for GHz Band Noise
220 Ω at 100 MHz, 260 Ω at 1 GHz, 2000 mA
BLM18EG221SN1 - Murata
Table 19: Suggested components to reduce ripple / noise on VCC
☞
☞☞
☞
The necessity of each part depends on the specific design, but it is recommended to provide all the parts described
in Figure 27 / Table 19 if the application device integrates an internal antenna.