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SARA-G3 series - System Integration Manual

UBX-13000995 - R06 Objective Specification Design-in

Page 98 of 218

To avoid voltage drop undershoot and overshoot at the start and end of a transmit burst during a GSM

call (when current consumption on the VCC supply can rise up to 1.9 A in the worst case), place a

bypass capacitor with large capacitance (more than 100 µF) and low ESR near the VCC pins, for

example:

 330 µF capacitance, 45 m ESR (e.g. KEMET T520D337M006ATE045, Tantalum Capacitor)

The use of very large capacitors (i.e. greater then 1000 µF) on the VCC line should be carefully

evaluated, since the voltage at the VCC pins must ramp from 2.5 V to 3.2 V within 4 ms to switch on

the module that otherwise can be switched on by a low level on PWR_ON pin.

To reduce voltage ripple and noise, especially if the application device integrates an internal antenna, place

the following bypass capacitors near the VCC pins:

 100 nF capacitor (e.g Murata GRM155R61C104K) to filter digital logic noise from clocks and data

sources

 10 nF capacitor (e.g. Murata GRM155R71C103K) to filter digital logic noise from clocks and data

sources

 56 pF capacitor with Self-Resonant Frequency in 800/900 MHz range (e.g. Murata

GRM1555C1E560J) to filter transmission EMI in the GSM/EGSM bands

 15 pF capacitor with Self-Resonant Frequency in 1800/1900 MHz range (e.g. Murata

GRM1555C1E150J) to filter transmission EMI in the DCS/PCS bands

Figure 30Figure 30 shows the complete configuration but the mounting of each single component

depends on the application design: it is recommended to provide all the VCC bypass capacitors as

described in Figure 30Figure 30 and Table 16Table 16 if the application device integrates an

internal antenna.

GND

C3 C2

SARA-G3 series

VCC

3V8

Figure 30: Suggested schematic and layout design for the VCC bypass capacitors to reduce ripple / noise on VCC voltage profile and to

avoid undershoot / overshoot on VCC voltage drops

Formatted: French (France)

u-blox SARA-G3 Series User Manual

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