2450BM14A0002 Matched Balun for Nordic nRF24L01/nRF24L01+

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 JTI Photograph Reference Design 2450BM14A0002

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).

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.

2450BM15A0002 matched for the nRF24L01/nRF24L01+ ICs

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.

The traditional reference design for RF balun has been the discrete solution shown in Figure 2.

Figure 2 Discrete Traditional Reference Design 2450BM14A0002
Figure 2. Discrete Reference Design

3. Layout

Figure 3 2450BM14A0002 Layer 1 of the Reference Design 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.

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.

2450BM14A0002 Fundamental
2450BM14A0002 Fundamental Hi
Fundamental Hi
2450BM14A0002 Fundamental Mid
Fundamental Mid
2450BM14A0002 2nd Harmonic
2nd Harmonic
2450BM14A0002 3rd Harmonic
3rd Harmonic
2450BM14A0002 4th Harmonic
4th Harmonic

Figure 4. Active Measurement Results

2450BM14A0002 Carrier Sweep
Carrier Sweep
2450BM14A0002 2nd Harmonic Sweep
2nd Harmonic Sweep
2450BM14A0002 3rd Harmonic Sweep
3rd Harmonic Sweep
2450BM14A0002 4th Harmonic Sweep
4th Harmonic Sweep

Appendix A

2450BM14A0002 Appendix-A 2450BM14A0002 Appendix-A page 2