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). www.johnsontechnology.com 1 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 www.johnsontechnology.com 2 The traditional reference design for RF balun has been the discrete solution shown in Figure 2. Figure 2. Discrete Reference Design www.johnsontechnology.com 3 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. www.johnsontechnology.com 4 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 www.johnsontechnology.com 5 Carrier Sweep 2nd Harmonic Sweep 3rd Harmonic Sweep 4th Harmonic Sweep Figure 5. Sweep Measurement Results www.johnsontechnology.com 6 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