Ublox SAM-M8Q Use and care manual

SAM-M8Q
Easy-to-use u-blox M8 GNSS antenna module
Hardware Integration Manual
Abstract
This document describes the hardware features and
specifications of the SAM-M8Q patch antenna module,
which features the u-blox M8 concurrent GNSS engine with
reception of GPS, GLONASS, Galileo and QZSS signals.
www.u-blox.com
UBX-16018358 - R05
Top and bottom view

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Document Information
Title
SAM-M8Q
Subtitle
Easy-to-use u-blox M8 GNSS antenna module
Document type
Hardware Integration Manual
Document number
UBX-16018358
Revision and Date
R05
24-Oct-2017
Document Status
Production Information
Document status explanation
Objective Specification
Document contains target values. Revised and supplementary data will be published later.
Advance Information
Document contains data based on early testing. Revised and supplementary data will be published later.
Early Production Information
Document contains data from product verification. Revised and supplementary data may be published later.
Production Information
Document contains the final product specification.
European Union regulatory compliance
SAM-M8Q smart antenna module complies with all relevant requirements for RED 2014/53/EU. The SAM-M8Q Declaration of Conformity
(DoC) is available at www.u-blox.com within Support > Product resources > Conformity Declaration.
This document applies to the following products:
Product name
Type number
Firmware version
PCN reference
SAM-M8Q
SAM-M8Q-0-10
ROM SPG 3.01
N/A
u-blox reserves all rights to this document and the information contained herein. Products, names, logos and designs described herein
may in whole or in part be subject to intellectual property rights. Reproduction, use, modification or disclosure to third parties of this
document or any part thereof without the express permission of u-blox is strictly prohibited.
The information contained herein is provided “as is” and u-blox assumes no liability for the use of the information. No warranty, either
express or implied, is given, including but not limited, with respect to the accuracy, correctness, reliability and fitness for a particular
purpose of the information. This document may be revised by u-blox at any time. For most recent documents, visit www.u-blox.com.
Copyright © 2017, u-blox AG.
u-blox is a registered trademark of u-blox Holding AG in the EU and other countries.

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Preface
u-blox Technical Documentation
As part of our commitment to customer support, u-blox maintains an extensive volume of technical
documentation for our products. In addition to our product-specific technical data sheets, the following manuals
are available to assist u-blox customers in product design and development.
GPS Compendium: This document, also known as the GPS book, provides a wealth of information
regarding generic questions about GPS system functionalities and technology.
Receiver Description including Protocol Specification: This document describes messages, configuration
and functionalities of the SAM-M8Q software releases and receivers.
Hardware Integration Manuals: These manuals provide hardware design instructions and information on
how to set up production and final product tests.
Application Notes: These documents provide general design instructions and information that applies to all
u-blox GNSS positioning modules.
How to use this Manual
This manual has a modular structure. It is not necessary to read it from beginning to end.
The following symbols highlight important information within the manual:
An index finger points out key information pertaining to module integration and performance.
A warning symbol indicates actions that could negatively influence or damage the module.
Questions
If you have any questions about SAM-M8Q integration, please:
Read this manual carefully.
Contact our information service on the homepage http://www.u-blox.com.
Read the questions and answers on our FAQ database on the homepage.
Technical Support
Worldwide Web
Our website (http://www.u-blox.com) is a rich pool of information. Product information, technical documents
and helpful FAQ can be accessed 24h a day.
By E-mail
If you have technical problems or cannot find the required information in the provided documents, contact the
closest Technical Support office. To ensure that we process your request as soon as possible, use our service pool
email addresses rather than personal staff email addresses. Contact details are at the end of the document.
Helpful Information when Contacting Technical Support
When contacting Technical Support please have the following information ready:
Receiver type (e.g. SAM-M8Q-0-10), Datacode (e.g. 180200.1000), and firmware version (e.g. ROM SPG
3.01)
Receiver/module configuration
Clear description of your question or the problem (may include a u-center logfile)
A short description of the application
Your complete contact details

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Contents
Preface ................................................................................................................................3
Contents..............................................................................................................................4
1Hardware description ..................................................................................................5
1.1 Overview .................................................................................................................................................................................5
1.2 Configuration ..........................................................................................................................................................................5
1.3 Connecting power ...................................................................................................................................................................5
1.4 Interfaces.................................................................................................................................................................................6
1.4.1 UART ..................................................................................................................................................................................6
1.4.2 Display Data Channel (DDC).................................................................................................................................................6
1.5 I/O pins....................................................................................................................................................................................7
1.5.1 RESET_N: Reset....................................................................................................................................................................7
1.5.2 EXTINT: External interrupt ....................................................................................................................................................7
1.5.3 TIMEPULSE ..........................................................................................................................................................................7
1.5.4 SAFEBOOT_N ......................................................................................................................................................................7
1.6 Electromagnetic interference on I/O lines...................................................................................................................................8
2Design ...........................................................................................................................9
2.1 Pin description .........................................................................................................................................................................9
2.2 Minimal design ........................................................................................................................................................................9
2.3 Footprint and paste mask .......................................................................................................................................................10
2.4 Antenna ................................................................................................................................................................................11
2.5 Embedded antenna operation.................................................................................................................................................12
2.6 PCB layout suggestion............................................................................................................................................................13
3Product handling........................................................................................................14
3.1 Packaging, shipping, storage and moisture preconditioning .....................................................................................................14
3.2 Soldering ...............................................................................................................................................................................14
3.3 EOS/ESD/EMI precautions .......................................................................................................................................................17
3.3.1 Electromagnetic interference (EMI) .....................................................................................................................................18
3.4 Applications with cellular modules ..........................................................................................................................................19
Appendix ..........................................................................................................................21
AGlossary ......................................................................................................................21
BRecommended parts ..................................................................................................21
Related documents...........................................................................................................22
Revision history................................................................................................................22
Contact..............................................................................................................................23

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1Hardware description
1.1 Overview
The SAM‑M8Q module is a concurrent GNSS patch antenna module featuring the high performance u-blox M8
GNSS engine with reception of GPS, GLONASS, Galileo and QZSS signals. Available in an LGA package, it is easy
to integrate and combines exceptional positioning performance with highly flexible power, design, and
connectivity options. SMT pads allow fully automated assembly with standard pick & place and reflow-soldering
equipment for cost-efficient, high-volume production enabling short time-to-market.
For product features see the SAM-M8Q Data Sheet [1].
To determine which u-blox product best meets your needs, see the product selector tables on the u-blox
website (www.u-blox.com).
1.2 Configuration
The configuration settings can be modified using UBX protocol configuration messages; see the u-blox 8 / u-blox
M8 Receiver Description Including Protocol Specification [2].The modified settings remain effective until power-
down or reset. If these settings have been stored in BBR (Battery Backed RAM), then the modified configuration
will be retained, as long as the backup battery supply is not interrupted.
1.3 Connecting power
The SAM‑M8Q antenna module has three power supply pins: VCC, VCC_IO and V_BCKP.
VCC: Main supply voltage
The VCC pin provides the main supply voltage. During operation, the current drawn by the module can vary by
some orders of magnitude, especially if enabling low-power operation modes. For this reason, it is important
that the supply circuitry be able to support the peak power for a short time (see the SAM-M8Q Data Sheet [1]
for specification).
When switching from backup mode to normal operation or at start-up, the SAM‑M8Q antenna module
must charge its internal capacitors in the core domain. In certain situations, this can result in a significant
current draw. For low power applications using power save and backup modes, it is important that the
power supply or low ESR capacitors at the module input can deliver this current/charge.
Use a proper GND concept. Do not use any series resistors, ferrite beads or coils in the power line.
The equipment must be supplied by an external limited power source in compliance with the clause 2.5 of
the standard IEC 60950-1.
VCC_IO: IO supply voltage
VCC_IO from the host system supplies the digital I/Os. The wide range of VCC_IO allows seamless interfacing to
standard logic voltage levels independent of the VCC voltage level. In many applications, VCC_IO is simply
connected to the main supply voltage.
Without a VCC_IO supply, the system will remain in reset state.
V_BCKP: Backup supply voltage
In case of a power failure on the module supply, V_BCKP supplies the real-time clock (RTC) and battery backed
RAM (BBR). Use of valid time and the GNSS orbit data at start-up will improve the GNSS performance, i.e. hot
starts and warm starts. If no backup battery is connected, the module performs a cold start at power-up.

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Avoid high resistance on the V_BCKP line: During the switch from main supply to backup supply, a short
current adjustment peak can cause high voltage drop on the pin with possible malfunctions.
If no backup supply voltage is available, connect the V_BCKP pin to VCC_IO.
As long a supply is connected to VCC_IO of SAM‑M8Q antenna module, the backup battery is
disconnected from the RTC and the BBR to avoid unnecessary battery drain (see Figure 1). In this case,
VCC_IO supplies power to the RTC and BBR. V_BCKP supplies the RTC and BBR in case VCC_IO voltage
goes below 1.4V.
Figure 1: Backup battery and voltage
1.4 Interfaces
1.4.1 UART
The SAM‑M8Q antenna module includes a Universal Asynchronous Receiver Transmitter (UART) serial interface,
RxD/TxD, which supports configurable baud rates, as specified in the SAM-M8Q Data Sheet [1]. The signal
output and input level is 0 V to VCC_IO. An interface based on RS232 standard levels (+/- 12 V) can be
implemented using level shifters, such as Maxim MAX3232. Hardware handshake signals and synchronous
operation are not supported.
1.4.2 Display Data Channel (DDC)
An I2C compatible Display Data Channel (DDC) interface is available with SAM‑M8Q antenna modules for serial
communication with an external host CPU. The interface only supports operation in slave mode (master mode is
not supported). The DDC protocol and electrical interface are fully compatible with the Fast-Mode of the I2C
industry standard. DDC pins SDA and SCL have internal pull-up resistors to VCC_IO.
For more information about the DDC implementation, see the u-blox 8 / u-blox M8 Receiver Description
Including Protocol Specification [2].For bandwidth information, see the SAM-M8Q Data Sheet [1].For timing
parameters, consult the I2C-bus specification [6].
The SAM-M8Q DDC interface supports serial communication with u-blox cellular modules. See the
specification of the applicable cellular module to confirm compatibility.
TX_READY
The TX_READY function is used to indicate when the receiver has data to transmit on DDC interface. A listener
can wait on the TX_READY signal instead of polling the DDC interfaces. The UBX-CFG-PRT message lets you
configure the polarity and the number of bytes in the buffer before the TX READY signal goes active. The
TX_READY function can be mapped to TXD (PIO 06). The TX_READY function is disabled by default.
The TX_READY functionality can be enabled and configured by AT commands sent to the u-blox cellular
module supporting the feature. For more information see the GPS Implementation and Aiding Features in
u-blox wireless modules [7].

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1.5 I/O pins
1.5.1 RESET_N: Reset
Driving RESET_N low activates a hardware reset of the system. Use this pin only to reset the module. Do not use
RESET_N to turn the module on and off, since the reset state increases power consumption. The SAM-M8Q
RESET_N pin is for input only.
The RTC time is also reset (but not BBR). Means the Hotstart performance will be degraded after a reset.
No additional capacitance should be added at RESET_N pin to GND (otherwise it could cause a reset at
startup).
1.5.2 EXTINT: External interrupt
EXTINT is an external interrupt pin with fixed input voltage thresholds with respect to VCC_IO (see the
SAM-M8Q Data Sheet [1] for more information). It can be used for wake-up functions in Power Save Mode on
and for aiding. Leave open if unused, function is disabled by default.
Power Control
The power control feature allows overriding the automatic active/inactive cycle of Power Save Mode. The state of
the receiver can be controlled through the EXTINT pin. The receiver can also be forced OFF using EXTINT when
Power Save Mode is not active.
Frequency aiding
The EXTINT pin can be used to supply time or frequency aiding data to the receiver.
For time aiding, hardware time synchronization can be achieved by connecting an accurate time pulse to the
EXTINT pin.
Frequency aiding can be implemented by connecting a periodic rectangular signal with a frequency up to 500
kHz and arbitrary duty cycle (low/high phase duration must not be shorter than 50 ns) to the EXTINT pin.
Provide the applied frequency value to the receiver using UBX messages.
1.5.3 TIMEPULSE
A configurable time pulse signal is available with SAM‑M8Q antenna module. By default, the time pulse signal is
configured to one pulse per second. For more information see the u-blox 8 / u-blox M8 Receiver Description
Including Protocol Specification [2].
1.5.4 SAFEBOOT_N
The SAFEBOOT_N pin is for future service, updates and reconfiguration.

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1.6 Electromagnetic interference on I/O lines
Any I/O signal line with a length greater than approximately 3 mm can act as an antenna and may pick up
arbitrary RF signals transferring them as noise into the GNSS receiver. This specifically applies to unshielded lines,
in which the corresponding GND layer is remote or missing entirely, and lines close to the edges of the printed
circuit board.
If, for example, a cellular signal radiates into an unshielded high-impedance line, it is possible to generate noise
in the order of volts and not only distort receiver operation but also damage it permanently.
On the other hand, noise generated at the I/O pins will emit from unshielded I/O lines. Receiver performance
may be degraded when this noise is coupled into the GNSS antenna (see Figure 11).
To avoid interference by improperly shielded lines, it is recommended to use resistors (e.g. R>20 ), ferrite beads
(e.g. BLM15HD102SN1) or inductors (e.g. LQG15HS47NJ02) on the I/O lines in series. These components should
be chosen with care because they will affect also the signal rise times.
Figure 2 shows an example of EMI protection measures on the RXD/TXD line using a ferrite bead. More
information can be found in section 3.3.
Figure 2: EMI Precautions

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2Design
2.1 Pin description
Function
PIN
No
I/O
Description
Remarks
Power
VCC
17
Main supply
Provide clean and stable supply (low impedance, < 0.2 Ohms).
GND
1, 4, 5, 6,
10, 11, 15,
16, 20
Ground
Assure a good GND connection to all GND pins of the module.
VCC_IO
2
VCC_IO
IO supply voltage. Must be always supplied. Usually connect to
VCC Pin 17
V_BCKP
3
Backup Supply
It is recommended to connect a backup supply voltage to V_BCKP
in order to enable Warm- and Hot Start features on the positioning
module. Otherwise, connect to VCC_IO.
UART
TXD
13
O
Serial Port
Can be configured as TX_Ready for DDC interface. Leave open if
not used.
RXD
14
I
Serial Port
Leave open if not used.
DDC
SCL
12
I
Serial Port
Leave open if not used.
SDA
9
I/O
Serial Port
Leave open if not used.
System
RESET_N
18
I
Reset (Active
Low)
Leave open if not used. Do not drive high. Do not connect a
capacitor at this pin.
TIMEPULSE
7
O
1PPS
Configurable Timepulse signal (one pulse per second by default).
Leave open if not used.
EXTINT
19
I
Ext. Interrupt
Leave open if not used.
SAFEBOOT_N
8
I
Leave open.
Table 1: SAM-M8Q Pinout
2.2 Minimal design
This is a minimal setup for a SAM-M8Q GNSS antenna module:
Figure 3: SAM-M8Q GNSS patch antenna design

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2.3 Footprint and paste mask
The suggested solder mask openings are the same as the pad layout.
Be sure to comply with special PCB layout design rules to ensure proper embedded antenna operation
when the customer PCB is used as part of antenna. This requires solid ground plane around the module,
see the section 2.60 for PCB layout suggestions.
Footprint
Figure 4: SAM-M8Q footprint
Symbol
Typ [mm]
A
15.50
B
7.60
C
3.80
D
R1.00
E
11.00
F
6.30
H
1.80
I
1.50
J
13.20
Table 2: SAM-M8Q footprint dimensions

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Paste mask
Stencil thickness: 120 µm
Orange: Pad
Grey: stencil opening
Figure 5: Suggested pad layout and occupied area, top view
Figure 6: Paste mask detail for each pad
2.4 Antenna
SAM-M8Q GNSS patch antenna module is designed with an integrated GPS/Galileo/GLONASS patch antenna.
Antenna input
The module has an embedded GNSS patch antenna and a SAW band-pass filter before LNA, which provides
excellent protection against out-of-band GNSS blocking caused by possible near-by wireless transmitters. The
signal is further amplified by the internal Low Noise Amplifier (LNA) inside u-blox’s UBX-M8030 GNSS chip.
Be sure to comply with special PCB layout design rules to ensure proper embedded antenna operation
when the customer PCB is used as part of antenna. This requires solid ground plane around the module,
see the section 2.6 for PCB layout suggestions.

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2.5 Embedded antenna operation
The embedded GPS/Galileo/GLONASS patch antenna provides optimal performance in the middle of a 50 x 50
mm ground plane.
Figure 7: 1.575 GHz typical free space radiation patterns
Tall nearby components (h > 3 mm) should be placed at least 10 mm away from the SAM-M8Q module. An
enclosure or plastic cover should have a minimum distance of 5 mm to the antenna.
Placement near a human body (or any biological tissue) can be acceptable by keeping a minimum distance of 10
mm between motherboard and the body. With smaller distances to the body, the radiation efficiency of the
antenna will start to reduce due to signal losses in biological tissue.

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2.6 PCB layout suggestion
For good performance, it is essential to have a proper layout and placement.
Figure 8: Layout recommendation (top layer)
SAM‑M8Q GNSS patch antenna module is intended to be placed in the middle of 50 x 50 mm GND size board,
but a larger or smaller ground plane can be used. When using smaller than 40 x 40 mm ground plane, the
performance may get decreased significantly.
Some important recommendations:
Easy to connect, but make sure all noisy lines / components are shielded or on inner layers
Do not place any noisy parts close to SAM-M8Q, place them as far away as possible or on other side of PCB
It is recommended not to place anything closer than 1 cm to each edge of SAM-M8Q
Performance goes significantly down if GND size is smaller than 40 x 40 mm
Use at least one layer for solid GND plane, preferably the layer SAM-M8Q is placed on it
Use solid GND plane under SAM-M8Q, which forms the shield. No signal traces allowed below SAM-M8Q
Route signal traces away from the module on top layer
When necessary, allow signal swap from top to bottom layer clearly away from module > 20 mm
Use copper pour ground planes on top and bottom layers; use multiple GND net via holes to tie separate
ground plane areas tightly together

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3Product handling
3.1 Packaging, shipping, storage and moisture preconditioning
For information pertaining to reels and tapes, Moisture Sensitivity levels (MSL), shipment and storage
information, as well as drying for preconditioning see the SAM-M8Q Data Sheet [1].
Population of Modules
When populating the modules, make sure that the pick and place machine is aligned to the copper pins
of the module and not to the module edge.
3.2 Soldering
Soldering paste
Use of "No Clean" soldering paste is highly recommended, as it does not require cleaning after the soldering
process has taken place. The paste listed in the example below meets these criteria.
Soldering Paste: OM338 SAC405 / Nr.143714 (Cookson Electronics)
Alloy specification: Sn 95.5/ Ag 4/ Cu 0.5 (95.5% Tin/ 4% Silver/ 0.5% Copper)
Melting Temperature: 217 °C
Stencil Thickness: 120 um
The final choice of the soldering paste depends on the approved manufacturing procedures.
The paste-mask geometry for applying soldering paste should meet the recommendations.
Reflow soldering
A convection type soldering oven is highly recommended over the infrared type radiation oven.
Convection heated ovens allow precise control of the temperature, and all parts will heat up evenly, regardless
of material properties, thickness of components and surface color.
As a reference, see the "IPC-7530 Guidelines for temperature profiling for mass soldering (reflow and wave)
processes”, published in 2001.
Preheat phase
During the initial heating of component leads and balls, residual humidity will be dried out. Note that this
preheat phase will not replace prior baking procedures.
Temperature rise rate: max. 3 °C/s. If the temperature rise is too rapid in the preheat phase it may cause
excessive slumping.
Time: 60 - 120 s. If the preheat is insufficient, rather large solder balls tend to be generated. Conversely, if
performed excessively, fine balls and large balls will be generated in clusters.
End Temperature: 150 - 200 °C. If the temperature is too low, non-melting tends to be caused in areas
containing large heat capacity.
Heating/ Reflow phase
The temperature rises above the liquidus temperature of 217 °C. Avoid a sudden rise in temperature as the
slump of the paste could become worse.
Limit time above 217 °C liquidus temperature: 40 - 60 s
Peak reflow temperature: 245 °C

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Cooling phase
A controlled cooling avoids negative metallurgical effects of the solder (becoming more brittle) and possible
mechanical tensions in the products. Controlled cooling helps to achieve bright solder fillets with a good shape
and low contact angle.
Temperature fall rate: max 4 °C/s
To avoid falling off, the SAM‑M8Q antenna module should be placed on the topside of the motherboard
during soldering.
The final soldering temperature chosen at the factory depends on additional external factors like choice of
soldering paste, size, thickness and properties of the baseboard, etc. Exceeding the maximum soldering
temperature in the recommended soldering profile may permanently damage the module.
Figure 9: Recommended soldering profile
SAM-M8Q module must not be soldered with a damp heat process.
Optical inspection
After soldering the SAM‑M8Q antenna module, consider an optical inspection step to check whether:
The module is properly aligned and centered over the pads.
Cleaning
In general, cleaning the populated modules is strongly discouraged. Residues underneath the modules cannot be
easily removed with a washing process.
Cleaning with water will lead to capillary effects where water is absorbed in the gap between the baseboard
and the module. The combination of residues of soldering flux and encapsulated water leads to short circuits
or resistor-like interconnections between neighboring pads.
Cleaning with alcohol or other organic solvents can result in soldering flux residues flooding into the two
housings, areas that are not accessible for post-wash inspections. The solvent will also damage the sticker
and the ink-jet printed text.
Ultrasonic cleaning will permanently damage the module, in particular the quartz oscillators.
The best approach is to use a "no clean" soldering paste and eliminate the cleaning step after the soldering.

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Repeated reflow soldering
Only single reflow soldering process is recommended for boards populated with SAM‑M8Q GNSS patch antenna
module. The SAM‑M8Q antenna module should not be submitted to two reflow cycles on a board populated
with components on both sides in order to avoid upside down orientation during the second reflow cycle. In this
case, the modules should always be placed on the side of the board that is submitted into the last reflow cycle.
The reason for this (besides others) is the risk of the module falling off due to the significantly higher weight in
relation to other components.
Repeated reflow soldering processes and soldering the module upside down are not recommended.
Wave soldering
Baseboards with combined through-hole technology (THT) components and surface-mount technology (SMT)
devices require wave soldering to solder the THT components. Only a single wave soldering process is
encouraged for boards populated with SAM‑M8Q antenna module.
Rework
The SAM-M8Q module can be unsoldered from the baseboard using a hot air gun. When using a hot air gun for
unsoldering the module, a maximum of one reflow cycle is allowed. In general, we do not recommend using a
hot air gun because this is an uncontrolled process and might damage the module.
Attention: use of a hot air gun can lead to overheating and severely damage the module.
Always avoid overheating the module.
After the module is removed, clean the pads before placing and hand soldering a new module.
Never attempt a rework on the module itself, e.g. replacing individual components. Such
actions immediately terminate the warranty.
Conformal coating
Certain applications employ a conformal coating of the PCB using HumiSeal®or other related coating products.
These materials affect the HF properties of the GNSS patch antenna module.
Conformal Coating of the module will void the warranty.
Casting
These materials affect the HF properties of the GNSS patch antenna including resonant frequency shifts and are
not suggested with SAM-M8Q.
Casting will void the warranty.
Use of ultrasonic processes
Some components on the SAM-M8Q module is sensitive to ultrasonic waves. Use of any ultrasonic processes
(cleaning, welding etc.) may cause damage to the GNSS Receiver.
u-blox offers no warranty against damages to the SAM‑M8Q antenna module caused by any ultrasonic
processes.
Oxidation of patch antenna
The patch antenna is metalized by silver paste and thus tends to oxidize and will change the color. This is normal
and is not a case for warranty.

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3.3 EOS/ESD/EMI precautions
When integrating GNSS positioning modules into wireless systems, careful consideration must be given to
electromagnetic and voltage susceptibility issues. Wireless systems include components that can produce
Electrical Overstress (EOS) and Electro-Magnetic Interference (EMI). CMOS devices are more sensitive to such
influences because their failure mechanism is defined by the applied voltage, whereas bipolar semiconductors
are more susceptible to thermal overstress. The following design guidelines are provided to help in designing
robust yet cost effective solutions.
To avoid overstress damage during production or in the field it is essential to observe strict
EOS/ESD/EMI handling and protection measures.
To prevent overstress damage at the RF_IN of your receiver, never exceed the maximum input
power (see the SAM-M8Q Data Sheet [1]).
Electrostatic discharge (ESD)
Electrostatic discharge (ESD) is the sudden and momentary electric current that flows between
two objects at different electrical potentials caused by direct contact or induced by an
electrostatic field. The term is usually used in the electronics and other industries to describe
momentary unwanted currents that may cause damage to electronic equipment.
ESD handling precautions
ESD prevention is based on establishing an Electrostatic Protective Area (EPA). The EPA can be a small working
station or a large manufacturing area. The main principle of an EPA is that there are no highly charging materials
near ESD sensitive electronics, all conductive materials are grounded, workers are grounded, and charge build-up
on ESD sensitive electronics is prevented. International standards are used to define typical EPA and can be
obtained for example from International Electrotechnical Commission (IEC) or American National Standards
Institute (ANSI).
GNSS positioning modules are sensitive to ESD and require special precautions when handling. Particular care
must be exercised when handling patch antennas, due to the risk of electrostatic charges. In addition to
standard ESD safety practices, the following measures should be taken into account whenever handling the
receiver.
Unless there is a galvanic coupling between the local GND (i.e. the
work table) and the PCB GND, then the first point of contact when
handling the PCB must always be between the local GND and PCB
GND.
Before mounting an antenna patch, connect ground of the device
When handling the RF pin, do not come into contact with any
charged capacitors and be careful when contacting materials that
can develop charges (e.g. patch antenna ~10 pF, coax cable ~50 -
80 pF/m, soldering iron, …)
To prevent electrostatic discharge through the RF input, do not
touch any exposed antenna area. If there is any risk that such
exposed antenna area is touched in non ESD protected work area,
implement proper ESD protection measures in the design.
When soldering RF connectors and patch antennas to the receiver’s
RF pin, make sure to use an ESD safe soldering iron (tip).
Failure to observe these precautions can result in severe damage to the GNSS module!

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GNSS positioning modules are sensitive to Electrostatic Discharge (ESD). Special precautions
are required when handling.
Electrical overstress (EOS)
Electrical overstress (EOS) usually describes situations when the maximum input power exceeds the maximum
specified ratings. EOS failure can happen if RF emitters are close to a GNSS receiver or its antenna. EOS causes
damage to the chip structures. If EOS damages the RF_IN, it is hard to determine whether the chip structures
have been damaged by ESD or EOS.
EOS protection measures
For designs with GNSS positioning modules and wireless (e.g. GSM/GPRS) transceivers in close proximity,
ensure sufficient isolation between the wireless and GNSS antennas. If wireless power output causes the
specified maximum power input at the GNSS RF_IN to be exceeded, employ EOS protection measures to
prevent overstress damage.
3.3.1 Electromagnetic interference (EMI)
Electromagnetic interference (EMI) is the addition or coupling of energy originating from any RF emitting device.
This can cause a spontaneous reset of the GNSS receiver or result in unstable performance. Any unshielded
line or segment (>3 mm) connected to the GNSS receiver can effectively act as antenna and lead to EMI
disturbances or damage.
The following elements are critical regarding EMI:
Unshielded connectors (e.g. pin rows etc.)
Weakly shielded lines on PCB (e.g. on top or bottom layer and especially at the border of a PCB)
Weak GND concept (e.g. small and/or long ground line connections)
EMI protection measures are recommended when RF emitting devices are near the GNSS receiver. To minimize
the effect of EMI a robust grounding concept is essential. To achieve electromagnetic robustness follow the
standard EMI suppression techniques.
http://www.murata.com/products/emc/knowhow/index.html
http://www.murata.com/products/emc/knowhow/pdf/4to5e.pdf
Improved EMI protection can be achieved by inserting a resistor (e.g. R > 20 ), or better yet a ferrite bead
(BLM15HD102SN1) or an inductor (LQG15HS47NJ02), into any unshielded PCB lines connected to the GNSS
receiver. Place the resistor as close as possible to the GNSS receiver pin.
Alternatively, feed-thru capacitors with good GND connection can be used to protect against EMI. A selection of
feed-thru capacitors are listed in Table 4.
Intended use
In order to mitigate any performance degradation of a radio equipment under EMC disturbance, system
integration shall adopt appropriate EMC design practice and not contain cables over three meters on
signal and supply ports.

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3.4 Applications with cellular modules
GSM terminals transmit power levels up to 2 W (+33 dBm) peak, 3G and LTE up to 250 mW continuous. Consult
the corresponding product data sheet in Related documents for the absolute maximum power input at the
GNSS receiver.
See the GPS Implementation and Aiding Features in u-blox wireless modules [7].
Isolation between GNSS and cellular antenna
In a handheld type design, an isolation of approximately 20 dB can be reached with careful placement of the
antennas. If such isolation cannot be achieved, e.g. in the case of an integrated cellular /GNSS antenna, an
additional input filter is needed on the GNSS side to block the high energy emitted by the cellular transmitter.
Examples of these kinds of filters would be the SAW Filters from Epcos (B9444 or B7839) or Murata.
Increasing interference immunity
Interference signals come from in-band and out-band frequency sources.
In-band interference
With in-band interference, the signal frequency is very close to the GNSS constellation frequency used, e.g. GPS
frequency of 1575 MHz (see Figure 10 ). Such interference signals are typically caused by harmonics from
displays, micro-controller, bus systems, etc.
1525 1550 1625
GPS input filter
characteristics
1575 1600
0
-110
Jammin
gsignal
1525 1550 1625
Frequency [MHz]
Power [dBm]
GPS input filter
characteristics
1575 1600
0
Jamming
signal
GPS
signals
GPSCarrier
1575.4 MHz
Figure 10: In-band interference signals
Figure 11: In-band interference sources

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Measures against in-band interference include:
Maintaining a good grounding concept in the design
Shielding
Layout optimization
Filtering
Placement of the GNSS antenna
Adding a CDMA, cellular, WCDMA band pass filter before handset antenna
Out-band interference
Out-band interference is caused by signal frequencies that are different from the GNSS carrier (see Figure 12).
The main sources are wireless communication systems such as cellular, CDMA, WCDMA, Wi-Fi, BT, etc.
Figure 12: Out-band interference signals
Measures against out-band interference include maintaining a good grounding concept in the design and keep
enough distance in between the antennas.
See the GPS Implementation and Aiding Features in u-blox wireless modules [7]