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NXP Semiconductors KW45B41Z Application Note

NXP Semiconductors KW45B41Z Application Note

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AN14098
KW45B41Z-LOC RF Test Report
Rev. 1 — 15 November 2023
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Keywords
Abstract
Content
AN14098, KW45B41Z, KW45B41Z-LOC, RF
The KW45B41Z localization (KW45B41Z-LOC) board is a highly configurable, low-power, and
cost-effective evaluation and development platform for NXP KW45B41Z MCU.
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Summary of Contents for NXP Semiconductors KW45B41Z

  • Page 1 KW45B41Z-LOC RF Test Report Rev. 1 — 15 November 2023 Application note Document information Information Content Keywords AN14098, KW45B41Z, KW45B41Z-LOC, RF Abstract The KW45B41Z localization (KW45B41Z-LOC) board is a highly configurable, low-power, and cost-effective evaluation and development platform for NXP KW45B41Z MCU.

  • Page 2: Introduction

    Two external antennas can be added attached to the board using the u.FL connectors. However, this platform can be used also for general application development. This document provides basic RF test results of the KW45B41Z localization board. The document describes the following sections: •...

  • Page 3: Acronyms

    Long Range Universal Serial Bus 3 Antenna-matching network estimation The KW45B41Z-LOC board uses the 2450AT42A100 Johanson chip antennas. It is important to perform a reflection coefficient measurement and estimate the matching circuit for a given PCB size and those antennas. AN14098 All information provided in this document is subject to legal disclaimers.
  • Page 4 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 1. KW45B41Z-LOC board with semirigid cables soldered for antenna reflection coefficient measurement The VNA port calibration plane is moved to the antenna PI filter using the port-extension function on the VNA. This was calibrated on short and open circuits. This is needed for precise measurement. The calibration plane is...
  • Page 5 AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report CAD Note: Keep the same length of the RF signals RF1 and RF4 in the layout RF_SMA_1 20279 -001E R110 10PF ANTENNA_2400MHZ RF_ANT_1 ANT_A 2.2nH ANTENNA A 10PF LQW15AN2N2C10 L11,L12 (Inductors) GCM1555C1H1R0BA16 RF_A...

  • Page 6: Antenna Gain Measurements

    AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 4. Reflection coefficient s11 – ANT_A Figure 5. Reflection coefficient s11 – ANT_B 4 Antenna gain measurements The antenna gain and efficiency listed below were measured after impedance matching. The board orientation and all the planes are in...

  • Page 7: Antenna Radiation Patterns

    AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 6. KW45B41Z-LOC board plane orientation during the radiation pattern measurement All the values in Table 4 were measured with three different frequencies. The highest average gain is achieved in the YZ plane. The ANT_A has slightly better efficiency in comparison with ANT_B.
  • Page 8 AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 7. ANT_A 3D radiation pattern Figure 8. The ANT_B 3D radiation pattern In addition, the 2D radiation patterns were measured for three planes at a frequency of 2440 MHz. This shows several cross-sections of the radiation. Both antennas have the lowest gain variation in the YZ plane. This also shows a relatively omni-directional radiation.
  • Page 9 AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 9. ANT_A - XY plane radiation pattern at 2440 MHz Table 5. ANT_A - XY plane radiation pattern at 2440 MHz Peak gain [dBi] Avg. gain [dBi] XY - plane -0.2 -4.1 AN14098 All information provided in this document is subject to legal disclaimers.
  • Page 10 AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 10. ANT_A - XZ plane radiation pattern at 2440 MHz Table 6. ANT_A - XZ plane radiation pattern at 2440 MHz Peak gain [dBi] Avg. gain [dBi] XZ - plane -4.7 AN14098 All information provided in this document is subject to legal disclaimers.
  • Page 11 AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 11. ANT_A - YZ plane radiation pattern at 2440 MHz Table 7. ANT_A - YZ plane radiation pattern at 2440 MHz Peak gain [dBi] Avg. gain [dBi] YZ - plane -1.3 AN14098 All information provided in this document is subject to legal disclaimers.
  • Page 12 AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 12. ANT_B - XY plane radiation pattern at 2440 MHz Table 8. ANT_B - XY plane radiation pattern at 2440 MHz Peak gain [dBi] Avg. gain [dBi] XY - plane -1.7 -3.9 AN14098 All information provided in this document is subject to legal disclaimers.
  • Page 13 AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 13. ANT_B - XZ plane radiation pattern at 2440 MHz Table 9. ANT_B - XZ plane radiation pattern at 2440 MHz Peak gain [dBi] Avg. gain [dBi] XZ - plane -4.4 AN14098 All information provided in this document is subject to legal disclaimers.

  • Page 14: Kw45B41Z Rf Ant Output Matching For Rx And Tx Operation

    6 KW45B41Z RF ANT output matching for RX and TX operation The KW45B41Z antenna RF input/output impedance value is not directly equal to 50 Ω. Therefore, the external RF matching circuit must be used. Moreover, the external DC component must be provided to the PA through the L2 inductor, which makes the matching-circuit design even more complex.
  • Page 15 RF_SW_CTL_ 3 CONTROL_3 Figure 15. Schematic of MCU antenna RF input/output used on KW45B41Z-LOC board A proper matching-circuit estimation must be done with a board modification. The HSWA4-63DR RF switch is removed and a semirigid cable is soldered to the input pad number 22. The measurement uses the VNA, whose port is calibrated and connected to the semirigid cable.

  • Page 16: Mcu Rf Output Matching For Rx Mode

    17. The KW45B41Z-LOC SDK package download, including all the example applications, is described in the KW45B41Z-LOC Board User Manual. Figure 17. Connectivity test application set the KW45B41Z-LOC into the RX mode The reflection coefficient s11 in the RX mode was measured with VNA, as shown in Figure 18.

  • Page 17: Mcu Rf Output Matching For Tx Mode

    AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 18. Reflection coefficient s11 of the RX mode 6.2 MCU RF output matching for TX mode The matching network is verified for the set of maximal RF output power +10 dBm. The KW45 radio is to...
  • Page 18 AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 19. Connectivity test application sets the KW45B41Z-LOC board into the TX mode The transmitted carrier frequency was set to 2410 MHz and the reflection coefficient s11 is shown in Figure Figure 20. Reflection coefficient s11 of the TX mode The measured values of the s11 for TX mode reached -11.88 dB at a frequency of 2.44 GHz.

  • Page 19: Kw45B41Z-Loc Board Rf Output Matching For Rx And Tx Operation

    7 KW45B41Z-LOC board RF output matching for RX and TX operation The KW45B41Z-LOC board RF input/output impedance was verified for receiving and transmitting operations, including the RF switch influence. The measurement was done with the RF signal routed to the u.FL connector J8.

  • Page 20: Kw45B41Z-Loc Board Rf Output Matching For Rx Mode

    This is considered as a very good achievement of the RX mode operation for the entire frequency range around 2.44 GHz. 7.2 KW45B41Z-LOC board RF output matching for TX mode +10 dBm The transmission operations are verified for the maximum RF output power of +10 dBm. The KW45 radio is to...

  • Page 21: Kw45B41Z-Loc Maximum Rf Output Power

    -11.98 8 KW45B41Z-LOC maximum RF output power The maximum TX output level was verified by the R&S Wireless Connectivity Tester CMW270 and KW45B41Z- LOC running the connectivity test application. This example application can switch the KW45 radio into the Generic FSK transmission mode and control the RF switch on the board. See Section 10.1...
  • Page 22 TX output level for the three frequencies. Additional attenuation must be added to reach correct output-level values. Table 13. Measured TX output levels of KW45B41Z-LOC board Measured TX output level [dBm] Real TX output level [dBm]...

  • Page 23: Kw45B41Z-Loc Rf Sensitivity Measurement

    R&S CMW270 Figure 26. RF sensitivity measurement – block diagram Figure 27. Sensitivity measurement of KW45B41Z-LOC board for BLE data rate of 1 Mbit/s on channel 20 Table 15 shows the sensitivity values for all measured data rates and three frequency channels.

  • Page 24: Software Support For Kw45B41Z-Loc Rf Measurements

    • Before testing, the Teraterm application (or other serial terminal emulator - PuTTY) must be installed on the PC. If it is not installed, install a serial terminal emulator application. • Plug a USB cable between the KW45B41Z-LOC board (J3) and the PC (USB Port). The LED3 (Green) turns AN14098 All information provided in this document is subject to legal disclaimers.
  • Page 25 • Open the Teraterm software. Select the “serial” option and click “OK”. • The port COM can change on each PC or connected KW45B41Z-LOC board (shown in the last step). • Go to the “Setup” tab and click the “Serial Port…” option.
  • Page 26 KW45B41Z-LOC RF Test Report Figure 30. Teraterm Serial port setup selection Select the COM port number that the KW45B41Z-LOC board is connected to. Figure 31. Teraterm Serial port setup selection In the “Serial port setup” window, select “115200” in the "speed" option and click the “OK” button.
  • Page 27 AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 32. Teraterm Serial COM port settings Note: In the "Terminal Setup", both "New-line Receive" and "New-line Transmit" should be set to "CR". • Push the SW1 (RST_SW) button to reset the board. The window shown in Figure 33 appears.
  • Page 28 AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report Figure 34. Main menu of the connectivity test application • Type “6” to select the RF switch activated output and a sub-menu appears. Type “1-5” to select one of the RF outputs. For example, number 4 activates the RF4 output (SMA2) for conductive measurements. Pres “p” to go into the previous menu.

  • Page 29: Configuration Of The Other Settings In The Connectivity Test Application

    10.2 Configuration of the other settings in the connectivity test application • After the KW45B41Z-LOC board reset, the main menu shows the connectivity test interface shortcuts. The menu shows how to switch between TX and RX operations, to increase or decrease the mode, channel, power, and so on.

  • Page 30: Conclusion

    Figure 40. Example of the parameters change during the running continuous test application • Detailed description of the connectivity test application is a part of the Kinetis K32W148/KW45B41Z Generic FSK Link Layer Software Quick Start Guide. This document is availiable in the SDK documenatation package.

  • Page 31: Revision History

    AN14098 NXP Semiconductors KW45B41Z-LOC RF Test Report 12 Revision history Table 17 summarizes the changes done to this document. Table 17. Revision history Revision number Release date Description 15 November 2023 Initial external release AN14098 All information provided in this document is subject to legal disclaimers.

  • Page 32: Legal Information

    NXP Semiconductors. In the event that customer uses the product for design-in and use in In no event shall NXP Semiconductors be liable for any indirect, incidental, automotive applications to automotive specifications and standards, punitive, special or consequential damages (including - without limitation - customer (a) shall use the product without NXP Semiconductors’...

  • Page 33: Table Of Contents

    Antenna-matching network estimation ..3 Antenna gain measurements ......6 Antenna radiation patterns ......7 KW45B41Z RF ANT output matching for RX and TX operation ........14 MCU RF output matching for RX mode ... 16 MCU RF output matching for TX mode ... 17 KW45B41Z-LOC board RF output matching for RX and TX operation ....19...

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