EFR32MG 2.4 GHz 19.5 dBm Radio Board
BRD4154A Reference Manual
The EFR32MG family of Wireless SoCs deliver a high performance, low energy wireless solution integrated into a small form
factor package.
By combining a high performance 2.4 GHz RF transceiver with an energy efficient 32-bit
MCU, the family provides designers the ultimate in flexibility with a family of pin-compatible devices that scale from 128/256 kB of flash and 16/32 kB of RAM. The ultra-low
power operating modes and fast wake-up times of the Silicon Labs energy friendly 32bit MCUs, combined with the low transmit and receive power consumption of the 2.4
GHz radio, result in a solution optimized for battery powered applications.
To develop and/or evaluate the EFR32 Mighty Gecko the BRD4154A Radio Board can
be connected to the Wireless Starter Kit Mainboard to get access to display, buttons and
additional features from Expansion Boards.
The EFR32 Mighty Gecko Radio Boards provide a development platform (together with the Wireless Starter Kit Mainboard) for the
Silicon Labs EFR32 Mighty Gecko Wireless System on Chips and serve as reference designs for the matching network of the RF interface.
The BRD4154A Radio Board is designed to the operate in the 2400-2483.5 MHz band with the RF matching network optimized to operate with 19.5 dBm output power.
To develop and/or evaluate the EFR32 Mighty Gecko the BRD4154A Radio Board can be connected to the Wireless Starter Kit Mainboard to get access to display, buttons and additional features from Expansion Boards and also to evaluate the performance of the RF
interface.
* Connection is not available by default.
Can be enabled through solderable jumpers. See the schematic of the Radio Board.
** Connection is only available through the on-board I/O expander. The associated I/O expander ports are shown in brackets.
BRD4154A Reference Manual
Radio Board Connector
2. Radio Board Connector
2.1 Introduction
The board-to-board connector scheme allows access to all EFR32MG1 GPIO pins as well as the RESETn signal. For more information
on the functions of the available pin functions, we refer you to the EFR32MG1 Datasheet.
2.2 Radio Board Connector Pin Associations
The figure below shows the pin mapping on the connector to the radio pins, to the I/O Expander pins (shown in brackets) and their
function on the Wireless Starter Kit Mainboard.
Figure 2.1. BRD4154A Radio Board Connector Pin Mapping
3. Radio Board Block Summary
Inverted-F
PCB
Antenna
2.4 GHz RF
UFL
Connector
LF
Crystal
32.768k
HF
Crystal
38.4M
Radio
Board
Connectors
8 Mbit
MX25R
Serial Flash
I2C
24AA0024
Serial EEPROM
Matching
Network &
Path
Selection
GPIO
UART
Debug
Packet Trace
AEM
I2C
SPI
SPI
2.4 GHz RF
2.4 GHz RF
EFM8
I/O Expander
I2C
Debug
GPIO
EFR32
EFR32
Wireless SoC
3.1 Introduction
This section gives a short introduction to the blocks of the BRD4154A Radio Board.
3.2 Radio Board Block Diagram
The block diagram of the BRD4154A Radio Board is shown in the figure below.
BRD4154A Reference Manual
Radio Board Block Summary
Figure 3.1. BRD4154A Block Diagram
3.3 Radio Board Block Description
3.3.1 Wireless MCU
The BRD4154A EFR32 Mighty Gecko Radio Board incorporates an EFR32MG1P732F256GM32 Wireless System on Chip featuring
32-bit Cortex-M4 with FPU core, 256 kB + 512 kB of flash memory and 32 kB of RAM and a 2.4 GHz band transceiver with output
power up to 19.5 dBm. For additional information on the EFR32MG1P732F256GM32, refer to the EFR32MG1 Data Sheet.
3.3.2 LF Crystal Oscillator (LFXO)
The BRD4154A Radio Board has a 32.768 kHz crystal mounted.
3.3.3 HF Crystal Oscillator (HFXO)
The BRD4154A Radio Board has a 38.4 MHz crystal mounted.
3.3.4 Matching Network for 2.4 GHz
The BRD4154A Radio Board incorporates a 2.4 GHz matching network which connects the 2.4 GHz TRX pin of the EFR32MG1 to the
one on-board printed Inverted-F antenna. The component values were optimized for the 2.4 GHz band RF performace and current consumption with 19.5 dBm output power.
For detailed description of the matching network see Chapter 4.2.1 Description of the 2.4 GHz RF Matching.
3.3.5 Inverted-F Antenna
The BRD4154A Radio Board includes a printed Inverted-F antenna (IFA) tuned to have close to 50 Ohm impedance at the 2.4 GHz
band.
For detailed description of the antenna see Chapter 4.5 Inverted-F Antenna.
3.3.6 UFL Connector
To be able to perform conducted measurements Silicon Labs added an UFL connector to the Radio Board. The connector allows an
external 50 Ohm cable or antenna to be connected during design verification or testing.
Note: By default the output of the matching network is connected to the printed Inverted-F antenna by a series component. It can be
connected to the UFL connector as well through a series 0 Ohm resistor which is not mounted by default. For conducted measurements
through the UFL connector the series component to the antenna should be removed and the 0 Ohm resistor should be mounted (see
Chapter 4.2 Schematic of the RF Matching Network for further details).
3.3.7 Radio Board Connectors
Two dual-row, 0.05” pitch polarized connectors make up the BRD4154A Radio Board interface to the Wireless Starter Kit Mainboard.
For more information on the pin mapping between the EFR32MG1P732F256GM32 and the Radio Board Connector refer to Chapter
2.2 Radio Board Connector Pin Associations.
3.3.8 I/O Expander
Due to the I/O port constraint of the EFR32MG1P732F256GM32 the BRD4154A Radio Board has an EFM8 family MCU mounted as an
I/O port expander to be able to utilize additional Wireless Starter Kit Mainboard features (LEDs, display etc.).
For more information on the pin mapping between the I/O Expander and the Radio Board Connector refer to Chapter 2.2 Radio Board
This section gives a short introduction to the RF section of the BRD4154A.
4.2 Schematic of the RF Matching Network
The schematic of the RF section of the BRD4154A Radio Board is shown in the following figure.
BRD4154A Reference Manual
RF Section
Figure 4.1. Schematic of the RF Section of the BRD4154A
4.2.1 Description of the 2.4 GHz RF Matching
The 2.4 GHz matching connects the 2G4RF_IOP pin to the on-board printed Inverted-F Antenna. The 2G4RF_ION pin is connected to
ground. For higher output powers (13 dBm and above) beside the impedance matching circuitry it is recommended to use additional
harmonic filtering as well at the RF output. The targeted output power of the BRD4154A board is 19.5 dBm thus the RF output of the IC
is connected to the antenna through a four-element impedance matching and harmonic filter circuitry.
For conducted measurements the output of the matching network can also be connected to the UFL connector by relocating the series
R1 resistor (0 Ohm) to the R2 resistor position between the output of the matching and the UFL connector.
4.3 RF Section Power Supply
On the BRD4154A Radio Board the supply pin of the RF Analog Power (RFVDD) is connected directly ot the output of the on-chip DCDC converter while the supply for the 2.4 GHz PA (PAVDD) is provided directly by the mainboard. This way, by default, the DC-DC
converter provides 1.8 V for the RF analog section, the mainboard provides 3.3 V for the PA (for details, see the schematic of the
BRD4154A).
4.4 Bill of Materials for the 2.4 GHz Matching
The Bill of Materials of the 2.4 GHz matching network of the BRD4154A Radio Board is shown in the following table.
Table 4.1. Bill of Materials for the BRD4154A 2.4 GHz 19.5 dBm RF Matching Network