Silicon Labs EFR32MG, BRD4150B Reference Manual

EFR32MG 2.4 GHz / 915 MHz Dual Band

19.5 dBm Radio Board
BRD4150B 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 high performance sub-GHz RF and 2.4 GHz RF transceivers 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 32-bit MCUs, combined with the low transmit and receive power con­sumption of the sub-GHz and 2.4 GHz radios result in a solution optimized for battery
powered applications.

To develop and/or evaluate the EFR32 Mighty Gecko the BRD4150B Radio Board can
be connected to the Wireless Starter Kit Mainboard to get access to display, buttons and
additional features from Expansion Boards.

RADIO BOARD FEATURES

• Wireless SoC:
EFR32MG1P233F256GM48

• CPU core: ARM Cortex-M4 with FPU

• Flash memory: 256 kB

• RAM: 32 kB

• Dual band transceiver integrated in the
Wireless SoC: EFR32

• Operation frequencies: 2.4 GHz
+ 915 MHz

• Transmit power: 19.5 dBm

• 2.4 GHz: Integrated PCB antenna.

• 915 MHz: Single SMA connector both for
transmit and receive

• Crystals for LFXO and HFXO: 32.768 kHz
and 38.4 MHz.

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BRD4150B Reference Manual

Introduction

1. Introduction

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 networks of the RF in­terfaces.

The BRD4150B Radio Board supports dual-band operation with its integrated sub-GHz ISM band and 2.4 GHz band transceivers. The
sub-GHz section is designed to the operate in the US FCC 902-928 MHz band with an external whip antenna, the 2.4 GHz section is
designed to operate at the 2400-2483.5 MHz band with the on-board printed antenna. The matching networks are optimized to

19.5 dBm output power.

To develop and/or evaluate the EFR32 Mighty Gecko the BRD4150B 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
interfaces.

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GND

F9 / PA3 / VCOM.#RTS_#CS

3v3

NC / P36

P200

Upper Row

NC / P38
NC / P40
NC / P42
NC / P44

DEBUG.TMS_SWDIO / PF1 / F0

DISP_ENABLE / PD15 / F14

UIF_BUTTON0 / PF6 / F12

UIF_LED0 / PF4 / F10

VCOM.#CTS_SCLK / PA2 / F8

DEBUG.RESET / RADIO_#RESET / F4

DEBUG.TDO_SWO / PF2 / F2

DISP_SI / PC6 / F16

VCOM.TX_MOSI / PA0 / F6

PTI.DATA / PB12 / F20

DISP_EXTCOMIN / PD13 / F18

USB_VBUS

5V

Board ID SCL

GND

Board ID SDA

USB_VREG

F7 / PA1 / VCOM.RX_MISO

F5 / PA5 / VCOM_ENABLE

F3 / PF3 / DEBUG.TDI

F1 / PF0 / DEBUG.TCK_SWCLK

P45 / NC

P43 / NC

P41 / NC

P39 / NC

P37 / PD15 / SENSOR_ENABLE

F11 / PF5 / UIF_LED1
F13 / PF7 / UIF_BUTTON1
F15 / PC8 / DISP_SCLK
F17 / PD14 / DISP_SCS
F19 / PB13 / PTI.SYNC
F21 / PB11 / PTI.CLK

GND

VMCU_IN

VCOM.#CTS_SCLK / PA2 / P0

P201

Lower Row

VCOM.#RTS_#CS / PA3 / P2

UIF_BUTTON0 / PF6 / P4
UIF_BUTTON1 / PF7 / P6

GND

VRF_IN

P35 / PD15 / DISP_ENABLE

P7 / PC9

P5 / PC8 / DISP_SCLK

P3 / PC7

P1 / PC6 / DISP_SI

P33 / PD14 / DISP_SCS

P31 / PD13 / DISP_EXTCOMIN

P29 / NC

P27 / NC

P25 / NC

P23 / NC

P21 / NC

P19 / NC

P17 / NC

P15 / NC

P13 / PC11

P11 / PA1 /VCOM.RX_MISO

P9 / PA0 / VCOM.TX_MOSI

NC / P34

UIF_LED1 / PF5 / P32

NC / P30

DEBUG.TDO_SWO / PF2 / P28

DEBUG.TMS_SWDIO / PF1 / P26

DEBUG.TMS_SWCLK / PF0 / P24

PTI.SYNC / PB13 / P22

PTI.DATA / PB12 / P20

PTI.CLK / PB11 / P18

VCOM_ENABLE / PA5 / P16

PA4 / P14

PC10 / P12

DEBUG.TDI / PF3 / P10

UIF_LED0 / PF4 / P8

BRD4150B 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 and their function on the Wireless Starter Kit Mainboard.

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Figure 2.1. BRD4150B Radio Board Connector Pin Mapping

3. Radio Board Block Summary

EFR32

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

SubGHz RF

Matching

Network &

DC Bias

SubGHz RF

SMA

Connector

EFR32

EFR32

Wireless SoC

3.1 Introduction

This section gives a short introduction to the blocks of the BRD4150B Radio Board.

3.2 Radio Board Block Diagram

The block diagram of the BRD4150B Radio Board is shown in the figure below.

BRD4150B Reference Manual

Radio Board Block Summary

Figure 3.1. BRD4150B Block Diagram

3.3 Radio Board Block Description

3.3.1 Wireless MCU

The BRD4150B EFR32 Mighty Gecko Radio Board incorporates an EFR32MG1P233F256GM48 Wireless System on Chip featuring
32-bit Cortex-M4 with FPU core, 256 kB of flash memory 32 kB of RAM, an integrated 2.4 GHz band and an integrated sub-GHz ISM
band transceiver with output power up to 19.5 dBm. For additional information on the EFR32MG1P233F256GM48, refer to the
EFR32MG1 Data Sheet.

3.3.2 LF Crystal Oscillator (LFXO)

The BRD4150B Radio Board has a 32.768 kHz crystal mounted.

3.3.3 HF Crystal Oscillator (HFXO)

The BRD4150B Radio Board has a 38.4 MHz crystal mounted.

3.3.4 Matching Network for Sub-GHz

The BRD4150B Radio Board incorporates a sub-GHz matching network which connects both the sub-GHz TX and RX pins of the
EFR32MG1 to the one SMA connector to be able to transmit and receive with one antenna. The component values were optimized for
the 915 MHz 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 Sub-GHz RF Matching.

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BRD4150B Reference Manual

Radio Board Block Summary

3.3.5 Matching Network for 2.4 GHz

The BRD4150B 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 4.2.2 Description of the 2.4 GHz RF Matching.

3.3.6 Inverted-F Antenna

The BRD4150B 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 4.6 Inverted-F Antenna.

3.3.7 SMA connector

To be able to perform conducted measurements or mount external antenna for radiated measurements, range tests etc., Silicon Labs
added an SMA connector to the Radio Board. The connector allows an external 50 Ohm cable or antenna to be connected during de­sign verification or testing.

3.3.8 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).

3.3.9 Radio Board Connectors

Two dual-row, 0.05” pitch polarized connectors make up the BRD4150B Radio Board interface to the Wireless Starter Kit Mainboard.

For more information on the pin mapping between the EFR32MG1P233F256GM48 and the Radio Board Connector refer to Chapter

2.2 Radio Board Connector Pin Associations.

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4. RF Section

GND

GND

GND

GND

VBIAS

GND

C1

C6

C10

L2

C3

C7

P2

U.FL

3
2

1

C4

Ground

RF I/ORF Crystal

RF Analog Power

PA Power

U1B
EFR32

2G4RF_IOP

20

2G4RF_ION

19

RFVDD

9

HFXI

10

HFXO

11

PAVDD

21

RFVSS

17

PAVSS

18

SUBGRF_OP

13

SUBGRF_ON

14

SUBGRF_IP

15

SUBGRF_IN

16

C8

C2

R2
0R

NM

L4

L6

TP1

R1
0R

L3

BAL1

0900BL15C050

SE

1

BAL2

4

BAL1

3

BIAS

2

GND

5

N/C

6

AT1

INVERTED_F

P1

SMA

3

2

1

4
5

L7

L1

L5

C5

Sub-GHz Matching Network

TRX Matching &

Filter

Filter

Antenna

Connector

Inverted-F

Antenna

Test

Connector

TRX Matching

Discrete Balun

2.4 GHz Matching Network

Path Selection

GND

GND

GND

VDCDC

VDCDC

GND

VBIAS

X1

38.400 MHz

31

2
4

C107

10P

L102

BLM18AG601SN1

1 2

L103

BLM18AG601SN1

1 2

C102

100P

C103

10P

C106
220N

Supply Filtering

High Frequency

Crystal

Sub-GHz PA

Power Supply

4.1 Introduction

This section gives a short introduction to the RF section of the BRD4150B.

4.2 Schematic of the RF Matching Network

The schematic of the RF section of the BRD4150B Radio Board is shown in the following figure.

BRD4150B Reference Manual

RF Section

Figure 4.1. Schematic of the RF Section of the BRD4150B

The RF matching comprises two separate TX/RX matching networks: one for the sub-GHz RF path, the other for the 2.4 GHz RF path.

4.2.1 Description of the Sub-GHz RF Matching

The sub-GHz matching network connects the differential TX outputs and RX inputs of the sub-GHz RF port to the SMA connector while
transforming the impedances to 50 Ohm. Careful design procedure was followed to ensure that the RX input circuitry does not load
down the TX output path while in TX mode and that the TX output circuitry does not degrade receive performance while in RX mode.

The matching includes a differential impedance matching circuitry, a discrete balanced-unbalanced transformer and a filter section. The
targeted output power is 19.5 dBm at 915 MHz.

4.2.2 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 BRD4150B 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 0 Ohm resistor to the R2 position between the output of the matching and the UFL connector.

4.3 RF Section Power Supply

On the BRD4150B Radio Board the supply pin of the radio (RFVDD) is connected directly ot the output of the on-chip DC-DC converter
while the supply for the sub-GHz and 2.4 GHz power amplifiers (VBIAS) is provided directly by the Motherboard. This way, by default,
the DC-DC converter provides 1.8 V for the RF analog section, the Motherboard provides 3.3 V for the PAs (for details, see the sche­matic of the BRD4150B).

4.4 Bill of Materials for the sub-GHz Matching

The Bill of Materials of the sub-GHz matching network of the BRD4150B Radio Board is shown in the following table.

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BRD4150B Reference Manual

RF Section

Table 4.1. Bill of Materials for the BRD4150B 915 MHz 19.5 dBm RF Matching Network

Component name Value Manufacturer Part Number

BAL1 Balun Johanson Technology 0900BL15C050

C3 1.8 pF Murata GRM1555C1H1R8WA01

C4 1.8 pF Murata GRM1555C1H1R8WA01

C5 3.9 pF Murata GRM1555C1H3R9WA01

C6 3.3 pF Murata GRM1555C1H3R3BA01

C7 5.6 pF Murata GRM1555C1H5R6BA01

C8 3.3 pF Murata GRM1555C1H3R3BA01

C10 56 pF Murata GRM1555C1H560GA01

L3 3.3 nH Murata LQW15AN3N3B80

L4 3.3 nH Murata LQW15AN3N3B80

L5 18 nH Murata LQW15AN18NG00

L6 10 nH Murata LQW15AN10NJ00

L7 10 nH Murata LQW15AN10NJ00

4.5 Bill of Materials for the 2.4 GHz Matching

The Bill of Materials of the 2.4 GHz matching network of the BRD4150B Radio Board is shown in the following table.

Table 4.2. Bill of Materials for the BRD4150B 2.4 GHz 19.5 dBm RF Matching Network

Component name Value Manufacturer Part Number

C1 2.0 pF Murata GRM1555C1H2R0WA01

C2 1.0 pF Murata GRM1555C1H1R0WA01

L1 1.8 nH Murata LQP15MN1N8W02

L2 3.0 nH Murata LQP15MN3N0W02

4.6 Inverted-F Antenna

The BRD4150B Radio Board includes an on-board printed Inverted-F Antenna tuned for the 2.4 GHz band. Due to the design restric­tions of the Radio Board the input of the antenna and the output of the matching network can't be placed directly next to each other thus
a 50 Ohm transmission line was necessary to connect them. The resulting impedance and reflection measured at the output of the
matcing network are shown in the following figure. As it can be observed the impedance is close to 50 Ohm (the reflection is better than

-10 dB) for the entire 2.4 GHz band.

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