2450BM14A0002 Matched Balun for Nordic nRF24L01/nRF24L01+
Johanson Technology, Inc. Highly temperature-stable Impedance Matched RF Front End Differential Balun-Low Pass Filter Integrated Ceramic Component For the Texas Instruments’ CC253X, CC254X, CC257X, CC853X and CC852X Family of Chipsets
October 2012

 

1. Introduction

The CC2530, CC2531, CC2533, CC2538, CC2540, CC2541, CC2543, CC2544, CC2570, CC2571, CC8530, CC8531, CC8520, and CC8521 chipset family from Texas Instruments are single-chip solutions for 2.4 GHz Bluetooth, IEEE 802.15.4, RF4CE, ZigBee, ANT RF network processors, Smart ENergyand PurePath™ audio transmission.
Johanson Technology, Inc.’s 2450BM15A0002 Impedance Matched RF Front End Differential Balun-Low Pass Filter integrated passive component was specifically designed for use with the CC253X, CC254X, CC257X, CC853X and CC852X family of chipsets. This matched balun simplifies the RF front-end by considerably reducing component count and implementation area size.
Highly temperature stable ceramic is used to manufacture the 2450BM15A0002 which is optimum for temperature-varied applications such as lighting (rated 125C) or outdoor.
The 2450BM15A0002 is a six-pin device with small mechanical dimensions of only 2.0 mm x 1.25 mm x 0.7mm (EIA 0805) and an approximate footprint of 1.65 mm x 2.8 mm.

2450BM15A0002 six-pin device with small mechanical dimensions of only 2.0 mm x 1.25 mm x 0.7mm EIA 0805

 

2. Description of the Reference Design
The traditional reference design for the CC253X, CC254X, CC257X, CC853X and CC852X families have been the discrete solutions like the one shown in Figure 2. Johanson Technology has developed a single-SMD solution with a chip Balun-LPF that is especially matched for the aforementioned family of ICs. The alternate reference design is shown in Figure 3 (pin # and assignment may vary)

Figure 2. 2450BM15A0002 Discrete Reference Design example
Figure 2. Discrete Reference Design example

Figure 3. 2450BM15A0002 Johanson Integrated Reference Design example
Figure 3. Johanson Integrated Reference Design example

Referring to Figure 3, U2 is the JTI matched balun 2450BM15A0002. Please refer to Appendix A for the datasheet of this component.

Figure 4. 2450BM15A0002 Component Placement
Figure 4. Component Placement

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 CC253X, CC254X, CC257X, CC853X, CC852X and 2450BM15A0002.

Figure 5. Example of CC2530 Johanson Technology Reference Design Schematic (with 2450BM15A0002)
Figure 5. Example of CC2530 JTI Reference Design Schematic (with 2450BM15A0002)

3. Layout
Johanson’s 2450BM15A0002 Matched Balun-LPF enables the designer to reduce the layout area due to component cutback (to one component); furthermore, PCB sensitivity is also decreased compared to the discrete passive solution.

The layout greatly influences the RF performance. It is recommended to copy the reference design as closely as possible.

Figure 6. Layer 1 of the CC2530 JTI Reference Design Layout (with 2450BM15A0002)
Figure 6. Layer 1 of the CC2530 JTI Reference Design Layout (with 2450BM15A0002)

 

In the event that the reference design can not be copied, then the routing from the RF pins RF_P and RF_N must be symmetrical to the matched balun component, U2. 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.

Go to: http://www.ti.com/tool/cc2530balun-refdes to download the gerber files.

 

4. Measurement Results

All results presented in this chapter are based on measurements performed with CC2530EM JTI rev 1.0 Reference Design board with Johanson’s 2450BM15A0002. All measurement results presented are the average of each batch tested from typical devices. The output power and harmonics measurements were performed with 0xF5 settings.

Johanson’s 2450BM15A0002 Matched Balun-LPF offers improved 2nd and 3rd harmonic, it eases implementation and increases margin to FCC/ETSI compliance when compared to solution with discrete passives.

Note: all values are in dBm if not otherwise stated.

CC2530EM Johanson Technology rev 1.0 Reference Design board with Johanson’s 2450BM15A0002
All results presented in this chapter are based on measurements performed with CC2530EM JTI rev 1.0 Reference Design board with Johanson’s 2450BM15A0002

 

5. References

[1] IEEE Std. 802.15.4-2006: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specification for Low-Rate Wireless Personal Area Network (LR-WPAN) http://standards.ieee.org/getieee802/download/802.15.4-2006.pdf

 

Appendix A

2450BM15A0002 Appendix A

2450BM15A0002 Appendix A page 2