Integration Manual
Table Of Contents
- Document information
- Contents
- 1 System description
- 1.1 Overview
- 1.2 Architecture
- 1.3 Pin-out
- 1.4 Operating modes
- 1.5 Supply interfaces
- 1.5.1 Module supply input (VCC)
- 1.5.1.1 VCC supply requirements
- 1.5.1.2 VCC current consumption in LTE connected mode
- 1.5.1.3 VCC current consumption in 2G connected mode
- 1.5.1.4 VCC current consumption in ultra low power deep sleep mode
- 1.5.1.5 VCC current consumption in low power idle mode
- 1.5.1.6 VCC current consumption in active mode (PSM / low power disabled)
- 1.5.2 Generic digital interfaces supply output (V_INT)
- 1.5.1 Module supply input (VCC)
- 1.6 System function interfaces
- 1.7 Antenna interfaces
- 1.8 SIM interface
- 1.9 Data communication interfaces
- 1.10 Audio
- 1.11 General Purpose Input/Output
- 1.12 GNSS peripheral input output
- 1.13 Reserved pins (RSVD)
- 2 Design-in
- 2.1 Overview
- 2.2 Supply interfaces
- 2.2.1 Module supply (VCC)
- 2.2.1.1 General guidelines for VCC supply circuit selection and design
- 2.2.1.2 Guidelines for VCC supply circuit design using a switching regulator
- 2.2.1.3 Guidelines for VCC supply circuit design using LDO linear regulator
- 2.2.1.4 Guidelines for VCC supply circuit design using a rechargeable battery
- 2.2.1.5 Guidelines for VCC supply circuit design using a primary battery
- 2.2.1.6 Guidelines for external battery charging circuit
- 2.2.1.7 Guidelines for external charging and power path management circuit
- 2.2.1.8 Guidelines for particular VCC supply circuit design for SARA-R4x2
- 2.2.1.9 Guidelines for removing VCC supply
- 2.2.1.10 Additional guidelines for VCC supply circuit design
- 2.2.1.11 Guidelines for VCC supply layout design
- 2.2.1.12 Guidelines for grounding layout design
- 2.2.2 Generic digital interfaces supply output (V_INT)
- 2.2.1 Module supply (VCC)
- 2.3 System functions interfaces
- 2.4 Antenna interfaces
- 2.5 SIM interface
- 2.6 Data communication interfaces
- 2.7 Audio
- 2.8 General Purpose Input/Output
- 2.9 GNSS peripheral input output
- 2.10 Reserved pins (RSVD)
- 2.11 Module placement
- 2.12 Module footprint and paste mask
- 2.13 Thermal guidelines
- 2.14 Schematic for SARA-R4 series module integration
- 2.15 Design-in checklist
- 3 Handling and soldering
- 4 Approvals
- 4.1 Product certification approval overview
- 4.2 US Federal Communications Commission notice
- 4.3 Innovation, Science, Economic Development Canada notice
- 4.4 European Conformance CE mark
- 4.5 National Communication Commission Taiwan
- 4.6 ANATEL Brazil
- 4.7 Australian Conformance
- 4.8 GITEKI Japan
- 4.9 KC South Korea
- 5 Product testing
- Appendix
- A Migration between SARA modules
- B Glossary
- Related documentation
- Revision history
- Contact
SARA-R4 series - System integration manual
UBX-16029218 - R20 Design-in Page 70 of 129
C1-Public
SARA-R422M8S
31
ANT_GNSS
GND
SAW LNA
44
ANT_ON
Figure 41: Typical circuit for best performance and improved jamming immunity with GNSS passive antenna
The external LNA can be selected to deliver the performance needed by the application in terms of:
• Noise figure (sensitivity)
• Selectivity and linearity (robustness against jamming)
• Robustness against RF power
Depending on the characteristics of the supply source (DC/DC regulator, linear LDO regulator or other)
used to supply the external LNA, make sure some good filtering is in place for the external LNA supply
because of the noise on the external LNA supply line can affect the performance of the LNA itself:
consider adding a proper series ferrite bead (see Table 28 for possible suitable examples) and a proper
decoupling capacitor to ground with Self-Resonant Frequency in the GNSS frequency range (as for
example the 27 pF 0402 capacitor Murata GCM1555C1H270JA16) at the input of the external LNA
supply line.
It should be noted anyway that the insertion loss of the filter directly affects the system noise figure
and hence the system performance. The selected SAW filter has to provide very low loss (no more
than 1.5 dB) in the GNSS pass-band, beside providing very large attenuation (more than 40 to 60 dB)
in the out-of-band jammers’ cellular frequency bands (see Table 26 for possible suitable examples).
SARA-R422M8S already provides an integrated SAW filter and LNA (as illustrated in Figure 4). The
addition of such external components should be carefully evaluated, especially in case the application
power consumption should be minimized, since the LNA alone requires an additional supply current
of typically 5 to 20 mA.
Moreover, the first LNA of the input chain will dominate the receiver noise performance, therefore its
noise figure should be less than 2 dB. If the antenna is close to the receiver, then a good passive
antenna (see Table 29) can be directly connected to the receiver with a short (a few cm) 50 line.
From a noise point of view, this design choice offers comparable performance as an active antenna
with a long (~3 to 5m) cable attached to the application board by means of an SMA connector without
the increased power consumption and BOM cost. If the goal is to protect the GNSS receiver in a noisy
environment then an additional external SAW filter may be required. If a degradation in the C/No of 2
to 3 dB (depending on the choice of the filter) is not acceptable for the application, then, to
compensate for the filter losses and restore an adequate C/No level, an external LNA with good gain
and low noise figure (see Table 27) is to be considered.
Table 26 lists examples of SAW filters suitable for the GNSS RF input of SARA-R422M8S modules.
Manufacturer
Part number
Description
Murata
SAFFB1G56AC0F0A
GPS / SBAS / QZSS / GLONASS / Galileo / BeiDou RF band-pass SAW
filter with high attenuation in Cellular frequency ranges
Murata
SAFFB1G56AC0F7F
GPS / SBAS / QZSS / GLONASS / Galileo / BeiDou RF band-pass SAW
filter with high attenuation in Cellular frequency ranges
Table 26: Examples of GNSS band-pass SAW filters