4. RF Section
4.1 Introduction
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.
GND
GND
GND
L2
P1
U.FL
3
2
1
C2
Ground
RF I/O
RF Crystal
RF Analog Power
PA Power
U1B
EFR32
2G4RF_IOP
17
2G4RF_ION
16
RFVDD
9
HFXI
10
HFXO
11
PAVDD
18
RFVSS
14
PAVSS
15
L1
AT1
INVERTED_F
R2
0R
NM
R1
0R
C1
Path
Selection
Inverted-F
Antenna
2.4 GHz
Matching
Network
Test
Connector
TRX Matching &
Filter
GND
PAVDD
VDCDC
GND
HFXTAL_P
HFXTAL_N
C107
10P
L102
BLM18AG601SN1
1
2
L103
BLM18AG601SN1
1
2
C102
100P
C103
10P
C106
220N
Supply Filtering
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 DC-
DC 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
Component name
Value
Manufacturer
Part Number
L1
1.8 nH
Murata
LQP15MN1N8W02
L2
3.0 nH
Murata
LQP15MN3N0W00
C1
2.0 pF
Murata
GRM1555C1H2R0WA01
C2
1.0 pF
Murata
GRM1555C1H1R0WA01
BRD4154A Reference Manual
RF Section
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