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Johanson Technology, Inc. 2450BM14A0002 Matched Balun for the
Nordic nRF24L01/nRF24L01+ Chipsets
November 2009
1. Introduction
The nRF24L01/nRF24L01+ from Nordic Semiconductor is a 2.45GHz one chip, ultra low power
transceiver.
Johanson Technology’s, 2450BM14A0002 LPF-Balun was specifically designed for use with the
nRF24L01/nRF24L01+ chipsets. This matched balun greatly simplifies the RF front-end by
considerably reducing component count, system variability, implementation size area, and PCB
sensitivity.
Figure 1. Component picture.
The 2450BM14A0002 is an SMD six-pin LTCC device with a small foot print of only 1.6 mm x
0.8 mm (EIA 0603).
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2. Description of the Reference Design
Johanson Technology has developed a solution with a chip Balun-Harmonic filter integrated
passive component that is especially matched for the nRF24L01/nRF24L01+ ICs, the
2450BM15A0002, shown in Figure 1.
p/n: 2450BM14A0001
Figure 2. Integrated Reference Design
The rightmost is the JTI matched balun 2450BM14A0002.
Please refer to Appendix A for the datasheet of the balun filter component. For more updated
information from the Johanson Technology web site at:
http://johansontechnology.com/en/integrated-passives/chipset-specific-baluns.html
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The traditional reference design for RF balun has been the discrete solution shown in Figure 2.
Figure 2. Discrete Reference Design
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3. Layout
Figure 3. Layer 1 of the Reference Design Layout
In the event that the reference design can not be copied, then the routing from the RF pins ANT1
and ANT2 must be symmetrical to the matched balun component, 2450BM14A0002. The length
of the tracks should be kept to a minimum and preferably the same length and width that are used
in the reference design. If this routing is not symmetrical, then the output power may be reduced
and the harmonics may increase.
The component placement influences the RF performance. It is recommended that the reference
PCB layout be copied as closely as possible. In particular, the designer should make note of all
dimensions between the nRF24L01/nRF24L01+ and 2450BM14A0002.
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4. Measurement Results
All results presented in this chapter are based on measurements performed with
nRF24L01/nRF24L01+ and 2450BM14A0002 Reference Design board. All measurement results
presented are the average of each batch tested from typical devices.
Johanson’s 2450BM14A0002 Harmonic Filter - Balun offers improved suppressed 2nd and 3rd
harmonics, it eases implementation and increases margin to FCC/ETSI compliance when
compared to solution with discrete passives.
Fundamental
Fundamental Hi
Fundamental Mid
2nd Harmonic
3rd Harmonic
4th Harmonic
Figure 4. Active Measurement Results
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Carrier Sweep
2nd Harmonic Sweep
3rd Harmonic Sweep
4th Harmonic Sweep
Figure 5. Sweep Measurement Results
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Appendix A
High Frequency Ceramic Solutions
2.45 GHz Impedance Matched Balun-Filter: Optimized for Nordic's Chipset nRF24L01/+
P/N 2450BM14A0002
Detail Specification: 11/12/10
Page 1 of 2
General Specifications
Part Number
2450BM14A0002
Insertion Loss
2.0 dB max.
Frequency (MHz)
2400 - 2500
Return Loss
9.5 dB min.
50 Ω
Phase Difference
160° ± 15°
Differential Balanced Impedance
Conjugate match to Nordic
nRF24L01/nRF24L01+
Amplitude Difference
3.5 ± 1.5 dB
Attenuation: Differential Mode
15 min.@4800~5000MHz
15 min.@7200~7500MHz
Operating Temperature
Attenuation: Common Mode
20 min.@4800~5000MHz
Unbalanced Impedance
P/N
Suffix
4,000
Reel Quanity
Storage Temperature
Packaging
Style
Bulk
Suffix = S
Eg. 2450BM14A0002S
T&R
Suffix = E
Eg. 2450BM14A0002E
Termination
Style
100% Tin
Suffix = None
Eg. 2450BM14A0002(E or S)
Tin / Lead
Please consult Factory
Terminal Configuration
0.063
± 0.004
1.60
± 0.10
W
0.031
± 0.004
0.80
± 0.10
T
0.024
± 0.004
0.60
± 0.10
a
0.008
± 0.004
0.20
± 0.10
b
0.008 +.004/-.006
0.20 +0.1/-0.15
c
0.006
± 0.004
0.15
± 0.10
g
0.012
± 0.004
0.30
± 0.10
p
0.020
± 0.002
0.50
± 0.05
2
GND
3
Balanced Port
4
Balanced Port
5
DC Feed+RF GND or
GND
W
NC
6
c
L
Function
Unbalanced Port
1
mm
L
+5 to +35°C, Humidity:
45-75%RH, 12 mos. Max
No.
Mechanical Dimensions
In
-40 to +85°C
a
3
2
1
4
5
6
p
T
g
b
Mounting Considerations
Mount these devices with maroon mark facing up.
*Line width should be designed to provide 50 Ω
0.25
impedance matching characteristics.
Solder Resist
*
*
Land
0.3
2.2nF
Capacitor*
0.55
Through-hole ( φ 0.35)
*
0.25
*With DC Feed
Units: mm
Johanson Technology, Inc. reserves the right to make design changes without notice.
The latest specification can be downloaded from the following link:
http://johansontechnology.com/en/integrated-passives/chipset-specific-baluns.html
www.johnsontechnology.com
7
High Frequency Ceramic Solutions
2.45 GHz Impedance Matched Balun-Filter: Optimized for Nordic's Chipset nRF24L01/+
P/N 2450BM14A0002
Detail Specification: 11/12/10
Page 2 of 2
Typical Electrical Performance (T=25°C)
0
)
)
Att_CM_dB
RL_dB
IL_dB
-10
-20
-30
-40
-50
)
1
2
3
)
)
4
5
6
7
8
freq, GHz
)
Johanson Technology, Inc. reserves the right to make design changes without notice.
All sales are subject to Johanson Technology, Inc. terms and conditions.
The latest specification can be downloaded from the following link:
http://johansontechnology.com/en/integrated-passives/chipset-specific-baluns.html
www.johnsontechnology.com
8
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