Silicon Laboratories BG22 Explorer Kit User manual

UG509: BG22 Explorer Kit User's Guide
The BG22 Explorer Kit is an ultra-low cost, small form factor devel-
opment and evaluation platform for the EFR32BG22 Wireless
Gecko System-on-Chip.
The BG22 Explorer Kit is focused on rapid prototyping and concept creation of IoT appli-
cations. It is designed around the EFR32BG22 SoC, which is an ideal device family for
developing energy-friendly connected IoT applications.
The kit features a USB interface, an on-board SEGGER J-Link debugger, one user-LED
and button, and support for hardware add-on boards via a mikroBus socket and a Qwiic
connector. The hardware add-on support allows developers to create and prototype ap-
plications using a virtually endless combination of off-the-shelf boards from mikroE,
sparkfun, AdaFruit, and Seeed Studios.
TARGET DEVICE
• EFR32BG22 Wireless Gecko System-on-
Chip (EFR32BG22C224F512IM40)
• High performance 2.4 GHz radio
• 32-bit ARM® Cortex®-M33 with 76.8 MHz
maximum operating frequency
• 512 kB flash and 32 kB RAM
KIT FEATURES
• User LED and push button
• 20-pin 2.54 mm breakout pads
•mikroBUS™ socket
• Qwiic® connector
• SEGGER J-Link on-board debugger
• Virtual COM port
• Packet Trace Interface (PTI)
• USB-powered
SOFTWARE SUPPORT
• Simplicity Studio™
ORDERING INFORMATION
• BG22-EK4108A
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Table of Contents
1. Introduction ................................
4
1.1 Kit Contents ...............................4
1.2 Getting Started ..............................4
1.3 Hardware Content .............................4
1.4 Kit Hardware Layout ............................5
2. Specifications ...............................6
2.1 Recommended Operating Conditions ......................6
2.2 Current Consumption ............................6
3. Hardware .................................7
3.1 Block Diagram ..............................7
3.2 Power Supply ..............................8
3.3 EFR32BG22 Reset ............................8
3.4 Push Button and LED............................8
3.5 On-board Debugger ............................9
3.6 Connectors ...............................10
3.6.1 Breakout Pads ............................11
3.6.2 MikroBUS Socket ...........................12
3.6.3 Qwiic Connector ............................13
3.6.4 Debug USB Micro-B Connector .......................13
4. Debugging ...............................14
4.1 On-board Debugger ............................14
4.2 Virtual COM Port .............................14
5. Radio .................................15
5.1 RF Section ...............................15
5.1.1 Description of the RF Matching .......................15
5.1.2 RF Section Power Supply .........................15
5.1.3 RF Matching Bill of Materials ........................16
5.1.4 Antenna ...............................16
5.1.5 Antenna Matching Bill of Materials ......................17
5.2 EMC Regulations for 2.4 GHz .........................17
5.2.1 ETSI EN 300-328 Emission Limits for the 2400-2483.5 MHz Band ...........17
5.2.2 FCC15.247 Emission Limits for the 2400-2483.5 MHz Band .............17
5.2.3 Applied Emission Limits .........................17
5.3 Relaxation with Modulated Carrier .......................18
5.4 Radiated Power Measurements ........................18
5.4.1 Maximum Radiated Power Measurement ...................19
5.4.2 Antenna Pattern Measurement .......................20
5.5 EMC Compliance Recommendations ......................22
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5.5.1 Recommendations for 2.4 GHz ETSI EN 300-328 Compliance ............22
5.5.2 Recommendations for 2.4 GHz FCC 15.247 Compliance ..............22
6. Schematics, Assembly Drawings, and BOM ...................23
7. Kit Revision History and Errata .......................24
7.1 Revision History .............................24
7.2 Errata .................................24
8. Board Revision History and Errata ......................25
8.1 Revision History .............................25
8.2 Errata .................................25
9. Document Revision History .........................26
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1. Introduction
The BG22 Explorer Kit has been designed to inspire customers to make IoT devices with the Silicon Labs EFR32BG22 Wireless Gecko
System-on-Chip. The kit includes a mikroBUS™ socket and Qwiic® connector, allowing users to add features to the kit with a large
selection of off-the-shelf boards.
Programming the BG22 Explorer Kit is easily done using a USB Micro-B cable and the on-board J-Link debugger. A USB virtual COM
port provides a serial connection to the target application, and the Packet Trace Interface (PTI) offers invaluable debug information
about transmitted and received packets in wireless links. The BG22 Explorer Kit is supported in Simplicity Studio™ and a Board Sup-
port Package (BSP) is provided to give application developers a flying start.
Connecting external hardware to the BG22 Explorer Kit can be done using the 20 breakout pads which present peripherals from the
EFR32BG22 Wireless Gecko such as I2C, SPI, UART and GPIOs. The mikroBUS socket allows inserting mikroBUS add-on boards
which interface with the EFR32BG22 through SPI, UART or I2C. The Qwiic connector can be used to connect hardware from the Qwiic
Connect System through I2C.
1.1 Kit Contents
The following items are included in the box:
• 1x BG22 Explorer Kit board (BRD4108A)
1.2 Getting Started
Detailed instructions for how to get started with your new BG22 Explorer Kit can be found on the Silicon Labs web page:
https://www.silabs.com/dev-tools
1.3 Hardware Content
The following key hardware elements are included on the BG22 Explorer Kit:
• EFR32BG22 Wireless Gecko SoC with 76.8 MHz operating frequency, 512 kB kB flash, and 32 kB RAM
• 2.4 GHz matching network and ceramic antenna for wireless transmission
• One LED and one push button
• On-board SEGGER J-Link debugger for easy programming and debugging, which includes a USB virtual COM port and Packet
Trace Interface (PTI)
• MikroBUS socket for connecting click boards™ and other mikroBUS add-on boards
• Qwiic connector for connecting Qwiic Connect System hardware
• Breakout pads for GPIO access and connection to external hardware
• Reset button
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Introduction
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1.4 Kit Hardware Layout
BG22 Explorer Kit layout is shown below.
Top View
Push Button
35.6 mm
55.9 mm
Reset Button
Breakout Pads
USB Micro-B Connector
- Virtual COM port
- Debug access
- Packet trace
LED
Qwiic
Connector
On-board USB
J-Link Debugger
mikroBUS Socket
EFR32BG22
Wireless Gecko
2.4 GHz
Chip Antenna
Figure 1.1. BG22 Explorer Kit Hardware Layout
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Introduction
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2. Specifications
2.1 Recommended Operating Conditions
Parameter Symbol Min Typ Max Unit
USB Supply Input Voltage VUSB – +5.0 – V
Supply Input Voltage (VMCU supplied externally) VVMCU +3.31V
Operating Temperature TOP – +20 – ˚C
Note: 1The typical supply voltage to the EFR32BG22 is 3.0 V, but the maximum voltage is a function of temperature and average life-
time current load. Over a 10-year lifespan, the average lifetime current load should not exceed 60 mA when the supply voltage is 3.3 V.
See the EFR32BG22 data sheet for more information.
2.2 Current Consumption
The operating current of the board greatly depends on the application and the amount of external hardware connected. The table below
attempts to give some indication of typical current consumptions for the EFR32BG22 and the on-board debugger. Note that the num-
bers are taken from the data sheets for the devices. For a full overview of the conditions that apply for a specific number from a data
sheet, the reader is encouraged to read the specific data sheet.
Table 2.1. Current Consumption
Parameter Symbol Condition Typ Unit
EFR32BG22 Current Con-
sumption1
IBG22 MCU current consumption in EM0 mode with all peripher-
als disabled (module supply voltage = 3.0 V, VSCALE2,
38.4 MHz crystal, CPU running Prime from flash at 25 °C)
28 µA/MHz
Radio system current consumption in receive mode, active
packet reception (VDD = 3.0 V, MCU in EM1 and all MCU
peripherals disabled, HCLK = 38.4 MHz, 1Mbit/s, 2GFSK,
f = 2.4 GHz at 25 °C)
3.8 mA
Radio system current consumption in transmit mode (VDD
= 3.0 V, MCU in EM1 and all MCU peripherals disabled,
HCLK = 38.4 MHz, f = 2.4 GHz, CW, 6 dBm output power
at 25 °C)
8.4 mA
On-board Debugger Sleep
Current Consumption 2
IDBG On-board debugger current consumption when USB cable
is not inserted (EFM32GG12 EM4S mode current con-
sumption)
80 nA
1 From EFR32BG22 data sheet
2From EFM32GG12 data sheet
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Specifications
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3. Hardware
The core of the BG22 Explorer Kit is the EFR32BG22 Wireless Gecko System-on-Chip. Refer to section 1.4 Kit Hardware Layout for
placement and layout of the hardware components.
3.1 Block Diagram
An overview of the BG22 Explorer Kit is illustrated in the figure below.
Memory
Radio
Device Connectivity & Debugging
J-Link
Debugger
USB Micro-B
Connector
2.4 GHz
Antenna
8 Mbit
MX25R
Button and LED
EFR32BG22
Wireless SoC
Breakout Pads
(EXP-Header pinout)
Expandability
Qwiic
Connector
mikroBUS
Socket
User Button
& LED
Mini-Simplicity
Connector
Serial Flash
Figure 3.1. Kit Block Diagram
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3.2 Power Supply
The kit is powered by the debug USB cable as illustrated in the figure below.
USB Micro-B LDO
5V0
IN OUT
Automatic
Isolation
3V3
VMCU
EFR32BG22
Wireless SoC
Peripherals
Peripherals
Peripherals
Peripherals
Figure 3.2. BG22 Explorer Kit Power Topology
The 5 V power net on the USB bus is regulated down to 3.3 V using an low-dropout regulator (LDO). An automatic isolation circuit
isolates the LDO when the USB cable is not plugged in.
Power can be injected externally on the VMCU net if the USB cable is removed and no other power sources are present on the kit.
Failure to follow this guideline can cause power conflicts and damage the LDO.
3.3 EFR32BG22 Reset
The EFR32BG22 can be reset by a few different sources:
• A user pressing the RESET button.
• The on-board debugger pulling the #RESET pin low.
3.4 Push Button and LED
The kit has one user push button, marked LED0, that is connected to a GPIO on the EFR32BG22. The button is connected to pin PC07
and it is debounced by an RC filter with a time constant of 1 ms. The logic state of the button is high while the button is not being
pressed, and low when the button is pressed.
The kit also features one yellow LED, marked LED0, that is controlled by a GPIO pin on the EFR32BG22. The LED is connected to pin
PA04 in an active-high configuration.
EFR32BG22
EFR32_LED0
EFR32_BUTTON0
User
Button & LED
PC07 (GPIO.EM4WU8)
PA04 (GPIO)
Figure 3.3. Button and LED
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3.5 On-board Debugger
The BG22 Explorer Kit contains a microcontroller separate from the EFR32BG22 Wireless Gecko that provides the user with an on-
board J-Link debugger through the USB Micro-B port. This microcontroller is referred to as the "on-board debugger", and is not pro-
grammable by the user. When the USB cable is removed, the on-board debugger goes into a very low power shutoff mode (EM4S),
consuming around 80 nA typically (EFM32GG12 data sheet number).
In addition to providing code download and debug features, the on-board debugger also presents a virtual COM port for general pur-
pose application serial data transfer. The Packet Trace Interface (PTI) is also supported which offers invaluable debug information
about transmitted and received packets in wireless links.
The figure below shows the connections between the target EFR32BG22 device and the on-board debugger.
Refer to chapter 4. Debugging for more details on debugging.
EFR32MG
EFR32BG22
PA01 (GPIO.SWCLK)
PA02 (GPIO.SWDIO)
PA03 (GPIO.SWV)
PA05 (USART1.TX)
PA06 (USART1.RX)
PA07 (USART1.RTS)
PA08 (USART1.CTS)
DBG_VCOM_TX
DBG_VCOM_RX
DBG_VCOM_CTS
DBG_VCOM_RTS
DBG_SWCLK
DBG_SWDIO
DBG_SWO
On-Board
J-Link
Debugger
Host
PC USB
DBG_PTI_DATA PC04 (FRC.DOUT)
PC05 (FRC.DFRAME)
DBG_PTI_FRAME
DBG_RESET RESETn
Figure 3.4. On-Board Debugger Connections
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Hardware
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3.6 Connectors
The BG22 Explorer Kit features a USB Micro-B connector, 20 breakout pads, a mikroBUS connector for connecting mikroBUS add-on
boards, and a Qwiic connector for connecting Qwiic Connect System hardware. The connectors are placed on the top side of the board,
and their placement and pinout are shown in the figure below. For additional information on the connectors, see the following sub chap-
ters.
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
PA4
RST
PA0
Breakout Pads
mikroBUS
Connector
USB Micro-B
Connector
J1 J2
J202
J201
GND
5V
PC7
PD3 - MIKROE_QWIIC_I2C_SDA
PD2 - MIKROE_QWIIC_I2C_SCL
PB1 - MIKROE_UART_TX
PB2 - MIKROE_UART_RX
PB3 - MIKROE_INT
PB4 - MIKROE_PWM
GND
VMCU
PC0 - MIKROE_SPI_MOSI
PC1 - MIKROE_SPI_MISO
PC2 - MIKROE_SPI_SCK
PC3 - MIKROE_SPI_CS
PC6 - MIKROE_RST
PB0 - MIKROE_ANALOG
Qwiic
Connector
P202
P900
Figure 3.5. BG22 Explorer Kit Connectors
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Hardware
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3.6.1 Breakout Pads
Twenty breakout pads are provided and allow connection of external peripherals. There are 10 pads on the left side of the board, and
10 pads on the right. The breakout pads contain a number of I/O pins that can be used with most of the EFR32BG22 Wireless Gecko's
features. Additionally, the VMCU (main board power rail), 3V3 (LDO regulator output), and 5V power rails are also exposed on the
pads.
The pin-routing on the Wireless Gecko is very flexible, so most peripherals can be routed to any pin. However, pins may be shared
between the breakout pads and other functions on the BG22 Explorer Kit. The table below includes an overview of the breakout pads
and functionality that is shared with the kit.
Table 3.1. Breakout Pads Pinout
Pin Connection Shared Feature
Left Side Breakout Pins
1 PC07 Button
2 PA04 LED
3 GND Ground
4 5V Board USB voltage
5 PD03 MikroBUS I2C_SDA, Qwiic I2C_SDA
6 PD02 MikroBUS I2C_SCL, Qwiic I2C_SCL
7 PB01 MikroBUS UART_TX
8 PB02 MikroBUS UART_RX
9 PB03 MikroBUS INT
10 PB04 MikroBUS PWM
Right Side Breakout Pins
1 RST EFR32BG22 reset, active low.
2 PA00
3 GND Ground
4 VMCU EFR32BG22 voltage domain
5 PC00 MikroBUS SPI_MOSI
6 PC01 MikroBUS SPI_MISO
7 PC02 MikroBUS SPI_SCK
8 PC03 MikroBUS SPI_CS
9 PC06 MikroBUS RST
10 PB00 MikroBUS Analog
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3.6.2 MikroBUS Socket
The BG22 Explorer Kit features a mikroBUS socket compatible with mikroBUS add-on boards. MikroBUS add-on boards can expand
the functionality of the kit with peripherals such as sensors and LCDs. Add-on boards follow the mikroBUS socket pin mapping and
communicate with the on-kit EFR32BG22 through UART, SPI or I2C. Several GPIOs are exposed on the mikroBUS socket. MikroBUS
add-on boards can be powered by the 5V or VMCU power rails, which are available on the mikroBUS socket.
The pinout of the EFR32BG22 on the kit is made such that all required peripherals are available on the mikroBUS socket. The I2C
signals are, however, shared with the Qwiic connector, and all mikroBUS signals are also routed to adjacent breakout pads.
When inserting a mikroBUS add-on board, refer to the orientation notch on the BG22 Explorer Kit, shown in the figure below, to ensure
correct orientation. Add-on boards have a similar notch that needs to be lined up with the one shown below.
mikroBUS
socket
Orientation notch
Figure 3.6. mikroBUS Add-on Board Orientation
The table below gives an overview of the mikroBUS socket pin connections to the EFR32BG22.
Table 3.2. mikroBUS Socket Pinout
mikro-
BUS Pin
Name
mikroBUS Pin
Function
Connection Shared Feature Suggested Peripheral Mapping
AN Analog PB00 BREAKOUT_RIGHT10 IADC0
RST Reset PC06 BREAKOUT_RIGHT9
CS SPI Chip Select PC03 BREAKOUT_RIGHT8 USARTx.CS
SCK SPI Clock PC02 BREAKOUT_RIGHT7 USARTx.CLK
MISO SPI Main Input
Secondary Output
PC01 BREAKOUT_RIGHT6 USARTx.RX
MOSI SPI Main Output
Secondary Input
PC00 BREAKOUT_RIGHT5 USARTx.TX
PWM PWM output PB04 BREAKOUT_LEFT10 TIMER0.CCx
INT Hardware Interrupt PB03 BREAKOUT_LEFT9
RX UART Receive PB02 BREAKOUT_LEFT8 USARTx.RX
TX UART Transmit PB01 BREAKOUT_LEFT7 USARTx.TX
SCL I2C Clock PD02 QWIIC_I2C_SCL, BREAKOUT_LEFT6 I2Cx.SCL
SDA I2C Data PD03 QWIIC_I2C_SDA, BREAKOUT_LEFT5 I2Cx.SDA
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mikro-
BUS Pin
Name
mikroBUS Pin
Function
Connection Shared Feature Suggested Peripheral Mapping
3V3 VCC 3.3V power VMCU EFR32BG22 voltage domain
5V VCC 5V power 5V Board USB voltage
GND Reference Ground GND Ground
3.6.3 Qwiic Connector
The BG22 Explorer Kit features a Qwiic connector compatible with Qwiic Connect System hardware. The Qwiic connector provides an
easy way to expand the functionality of the BG22 Explorer Kit with sensors, LCDs, and other peripherals over the I2C interface. The
Qwiic connector is a 4-pin polarized JST connector, which ensures the cable is inserted the right way.
Qwiic Connect System hardware is daisy chain-able as long as each I2C device in the chain has a unique I2C address.
Note: The Qwiic I2C connections on the BG22 Explorer Kit are shared with the mikroBUS I2C signals.
The Qwiic connector and its connections to Qwiic cables and the EFR32BG22 are illustrated in the figure below.
Qwiic cable
GND
VMCU
SDA - PD3
SCL - PD2
Figure 3.7. Qwiic Connector
The table below gives an overview of the Qwiic connections to the EFR32BG22.
Table 3.3. Qwiic Connector Pinout
Qwiic Pin Connection Shared Feature Suggested Peripheral Mapping
Ground GND Ground
3.3V VMCU EFR32BG22 voltage domain
SDA PD03 MIKROE_I2C_SDA,
BREAKOUT_LEFT5
I2Cx.SDA
SCL PD02 MIKROE_I2C_SCL,
BREAKOUT_LEFT6
I2Cx.SCL
3.6.4 Debug USB Micro-B Connector
The debug USB port can be used for uploading code, debugging, and as a Virtual COM port. More information is available in section
4. Debugging.
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4. Debugging
The BG22 Explorer Kit contains an on-board SEGGER J-Link Debugger that interfaces to the target EFR32BG22 using the Serial Wire
Debug (SWD) interface. The debugger allows the user to download code and debug applications running in the target EFR32BG22.
Additionally, it provides a virtual COM port (VCOM) to the host computer that is connected to the target device's serial port, for general
purpose communication between the running application and the host computer. The Packet Trace Interface (PTI) is also supported by
the on-board debugger, which offers invaluable debug information about transmitted and received packets in wireless links. The on-
board debugger is accessible through the USB Micro-B connector.
4.1 On-board Debugger
The on-board debugger is a SEGGER J-Link debugger running on an EFM32 Giant Gecko. The debugger is directly connected to the
debug and VCOM pins of the target EFR32BG22.
When the debug USB cable is inserted, the on-board debugger is automatically activated, and takes control of the debug and VCOM
interfaces. This means that debug and communication will not work with an external debugger connected at the same time. The on-
board LDO is also activated, providing power to the board.
4.2 Virtual COM Port
The virtual COM port is a connection to a UART of the target EFR32BG22 and allows serial data to be sent and received from the
device. The on-board debugger presents this as a virtual COM port on the host computer that shows up when the USB cable is inser-
ted.
Data is transferred between the host computer and the debugger through the USB connection, which emulates a serial port using the
USB Communication Device Class (CDC). From the debugger, the data is passed on to the target device through a physical UART
connection.
The serial format is 115200 bps, 8 bits, no parity, and 1 stop bit by default.
Note: Changing the baud rate for the COM port on the PC side does not influence the UART baud rate between the debugger and the
target device.
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Debugging
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5. Radio
5.1 RF Section
This section gives a short introduction to the RF section of the BRD4108A board.
The schematic of the RF section is shown in the figure below.
VDCDC
GND
GND
GND
GND GND
GND
C12
120P
C5
NM
C3
0P1
C18
100N
NM
Gr ou n d
RF I / ORF Cr ys t a l
RF An a l o g Powe r
PA Powe r
U1B
EFR32BG22
2.4 GHz
Matching
Network
Supply
Filtering
High
Frequency
Crystal
Chip Antenna and
Antenna Matching Network
RF2G4_IO 14
RFVDD
12
HFXTAL_I
9
HFXTAL_O
10
PAVDD
15
RFVSS 13
R4
0R
C4
1P2
X1
38.4 MHz
31
2
4
Z9
16N
R5
0R
L1
2N7
C11
100N
NM
CC1
18P
ANT1
2450AT18D0100
GND 2 IN
1
GND 3 GND
4
Z7
1P6
Z8
NM
L2
3N0
C19
120P
Figure 5.1. Schematic of the RF Section
5.1.1 Description of the RF Matching
The impedance of the RF port of the EFR32BG22 is matched to 50 Ohm. The RF2G4_IO pin is connected to a four-element impedance
matching and harmonic filter circuitry, and a DC blocking capacitor.
Note: Due to the thicker PCB stack-up, the radiated level of the 5th harmonic has been increased. Therefore, compared to the 3-ele-
ment L-C-L matching networks presented in the AN930.2: EFR32 Series 2 2.4 GHz Matching Guide application note, the matching ap-
plied on the BRD4108A board has an additional small value capacitor in the C3 position, and small modification of the C4 capcitor was
also required. With these changes, the suppression of the radiated 5th harmonic was improved, and so its level is under the relevant
regulation limit.
The on-board ceramic antenna is also matched to 50 Ohm by its impedance matching components and connected to the EFR32BG22.
5.1.2 RF Section Power Supply
On the BRD4108A, the supply for the radio (RFVDD) and the power amplifier (PAVDD) is connected to the on-chip DC-DC converter.
By default, the DC-DC converter provides 1.8 V for the entire RF section (for details, see the BRD4108A schematic).
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5.1.3 RF Matching Bill of Materials
The BRD4108A RF matching network bill of materials is shown in the following table.
Table 5.1. BRD4108A RF Matching Network Bill of Materials
Component name Value Manufacturer Part Number
L1 2.7 nH Murata LQP03HQ2N7B02
L2 3 nH Murata LQP03HQ3N0B02
CC1 18 pF Murata GJM0335C1E180GB01D
C3 0.1 pF Murata GRM0335C1H0R1WA01D
C4 1.2 pF Murata GRM0335C1H1R2BA01D
C5 NM – –
5.1.4 Antenna
The BRD4108A has an on-board ceramic antenna.
The land pattern for the antenna on the PCB layout was designed based on the recommendations of the antenna data sheet. Because
there is a significant difference between the layout (practically the board size) of the BRD4108A and the antenna evaluation board, the
applied antenna matching network deviates from the recommendation.
The values of the antenna matching network components were fine-tuned to match the antenna impedance close to 50 Ohm on the
BRD4108A PCB. The resulting antenna impedance and reflection are shown in the figure below.
Figure 5.2. Fine-tuned Antenna Impedance (Blue Curve) and Reflection (Red Curve)
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5.1.5 Antenna Matching Bill of Materials
The BRD4108A antenna matching network bill of materials is shown in the following table.
Table 5.2. BRD4108A Antenna Matching Network Bill of Materials
Component name Value Manufacturer Part Number
ANT1 – Johanson 2450AT18D0100
Z7 16 nH Murata LQP03TN16NJ02D
Z9 1.6 pF Murata GRM0335C1H1R6BA01D
5.2 EMC Regulations for 2.4 GHz
5.2.1 ETSI EN 300-328 Emission Limits for the 2400-2483.5 MHz Band
Based on ETSI EN 300-328, the allowed maximum fundamental power for the 2400-2483.5 MHz band is 20 dBm EIRP. For the unwan-
ted emissions in the 1 GHz to 12.75 GHz domain, the specified limit is -30 dBm EIRP.
5.2.2 FCC15.247 Emission Limits for the 2400-2483.5 MHz Band
FCC 15.247 allows conducted output power up to 1 Watt (30 dBm) in the 2400-2483.5 MHz band. For spurious emissions the limit is
-20 dBc based on either conducted or radiated measurement, if the emission is not in a restricted band. The restricted bands are speci-
fied in FCC 15.205. In these bands the spurious emission levels must meet the levels set out in FCC 15.209. In the range from
960 MHz to the frequency of the 5th harmonic, it is defined as 0.5 mV/m at 3 m distance (equals to -41.2 dBm in EIRP).
In case of operating in the 2400-2483.5 MHz band the 2nd, 3rd and 5th harmonics can fall into restricted bands, so for those the
-41.2 dBm limit should be applied. For the 4th harmonic, the -20 dBc limit should be applied.
5.2.3 Applied Emission Limits
The overall applied limits are shown in the table below. For the harmonics that fall into the FCC restricted bands, the FCC 15.209 limit
is applied, and the ETSI EN 300-328 limit is applied for the rest.
Table 5.3. Applied Limits for Spurious Emissions
Harmonic Frequency Limit
2nd 4800~4967 MHz -41.2 dBm
3rd 7200~7450.5 MHz -41.2 dBm
4th 9600~9934 MHz -30 dBm
5th 12000~12417.5 MHz -41.2 dBm
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5.3 Relaxation with Modulated Carrier
Depending on the applied modulation scheme and the Spectrum Analyzer settings specified by the relevant EMC regulations, the
measured power levels are usually lower compared to the results with unmodulated carrier. These differences have been measured
and used as relaxation factors on the results of the radiated measurement performed with unmodulated carrier. This way, the radiated
compliance with modulated transmission can be evaluated.
In this case, both the ETSI EN 300-328 and the FCC 15.247 regulations define the following Spectrum Analyzer settings for measuring
the unwanted emissions above 1 GHz:
• Detector: Average
• RBW: 1 MHz
The table below shows the relative levels of the measured modulated signals compared to the unmodulated levels with the above
Spectrum Analyzer settings in case of the supported modulation schemes.
Table 5.4. Measured Relaxation Factors for the Supported Modulation Schemes
Applied Modulation
(Packet Length:
255 bytes)
BLE Coded PHY:
125 Kb/s (PRBS9) [dB]
BLE Coded PHY:
500 Kb/s (PRBS9) [dB]
BLE 1M PHY: 1 Mb/s
(PRBS9) [dB]
BLE 2M PHY: 2 Mb/s
(PRBS9) [dB]
2nd harmonic -2.7 -3.1 -3.3 -9.1
3rd harmonic -4.8 -5.2 -5.2 -10.7
4th harmonic -5.5 -6.5 -6.7 -11.9
5th harmonic -6.3 -6.5 -6.7 -11.4
As it can be observed, the BLE 125 Kb/s coded modulation scheme has the lowest relaxation factors. These values will be used as the
worst case relaxation factors for the radiated measurements.
5.4 Radiated Power Measurements
The output power of the EFR32BG22 was set to 6 dBm. The board was supplied through its USB connector by connecting to a PC
through a USB cable.
During the measurements, the board was rotated in three cuts. See the reference plane illustration in the figure below. The radiated
powers of the fundamental and the harmonics were measured with horizontal and vertical reference antenna polarizations.
Figure 5.3. DUT Reference Planes
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5.4.1 Maximum Radiated Power Measurement
The transceiver was operated in unmodulated carrier transmission mode and the output power of the radio was set to 6 dBm. The re-
sults are shown in the table below.
The correction factors are applied based on the BLE 125 Kb/s coded modulation, shown in section 5.3 Relaxation with Modulated Carri-
er. For the rest of the supported modulation schemes the correction factors are larger, thus the related calculated margins would be
higher compared to the ones shown in the table below. Thus, the below margins can be considered as worst case margins.
Table 5.5. Maximums of the Measured Radiated Powers of BRD4108A
Frequency
(2440 MHz)
Measured Un-
modulated EIRP
[dBm]
Orientation
BLE 125 Kb/s Coded Modulation
Limit in EIRP
[dBm]
Correction Fac-
tor [dB]
Calculated
Modulated EIRP
[dBm]
Modulated Mar-
gin [dB]
Fund 7.7 YZ/V NA (0 is used) 7.7 22.3 30.0
2nd -54.5 YZ/V -2.7 -57.2 16.0 -41.2
3rd -39.2 YZ/V -4.8 -44.0 2.8 -41.2
4th -50.5 XZ/H -5.5 -56.0 26.0 -30.0
5th -46.3 XY/V -6.3 -52.6 11.4 -41.2
As it it is shown in the table, with 6 dBm output power, the radiated power of the fundamental is higher than 6 dBm due to the antenna
gain. The 3rd harmonic is above the limit in case of the unmodulated carrier transmission. But with the relaxation of the supported mod-
ulation schemes, the margin is at least 2.8 dB.
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5.4.2 Antenna Pattern Measurement
The measured typical antenna patterns are shown in the figures below.
0°
45°
90°
135°
180°
225°
270°
315°
-50
-40
-30
-20
-10
0
Normalized Radiation Pattern [dB], XY cut
Horizontal
Vertical
Figure 5.4. Antenna Pattern - XY
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