SWRA640H December   2018  – May 2024 CC1310 , CC1312R , CC1314R10 , CC1350 , CC1352P , CC1352R , CC1354P10 , CC1354R10 , CC2620 , CC2630 , CC2640 , CC2640R2F , CC2640R2F-Q1 , CC2642R , CC2642R-Q1 , CC2650 , CC2652P , CC2652R , CC2652R7 , CC2652RB , CC2652RSIP , CC2674P10 , CC2674R10

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Reference Design
    1. 1.1 Sub-1GHz LaunchPads
      1. 1.1.1 LAUNCHXL-CC1310
      2. 1.1.2 LAUNCHXL-CC1312R
    2. 1.2 2.4GHz LaunchPads
      1. 1.2.1 LAUNCHXL-CC2640R2
      2. 1.2.2 LAUNCHXL-CC26x2R
      3. 1.2.3 LP-CC26x1
    3. 1.3 Dual-Band LaunchPads
      1. 1.3.1 LAUNCHXL-CC1350EU/US
      2. 1.3.2 LAUNCHXL-CC1350-4
      3. 1.3.3 LAUNCHXL-CC1352R
      4. 1.3.4 LAUNCHXL-CC1352P1
      5. 1.3.5 LAUNCHXL-CC1352P-2
      6. 1.3.6 LAUNCHXL-CC1352P-4
      7. 1.3.7 LP-CC1352P7-1
      8. 1.3.8 LP-CC1352P7-4
      9. 1.3.9 LP-EM-CC1354P10-6
    4. 1.4 Reference Design Overview
  5. 2 Front-End Configurations
    1. 2.1 Overview of Front-end Configurations
    2. 2.2 Configuring the Front-End Mode
    3. 2.3 CC13xx Single-Ended Mode
      1. 2.3.1 Single-Ended Modes
      2. 2.3.2 Single-Ended TX-Only
      3. 2.3.3 Single-Ended RX-Only
      4. 2.3.4 Single-Ended Modes - 2.4GHz
    4. 2.4 CC26xx Single-End Mode
  6. 3 Schematic
    1. 3.1 Schematic Overview
      1. 3.1.1 24/48MHz Crystal
      2. 3.1.2 32.768kHz Crystal
      3. 3.1.3 Balun
      4. 3.1.4 Filter
      5. 3.1.5 RX_TX Pin
      6. 3.1.6 Decoupling Capacitors
      7. 3.1.7 Antenna Components
      8. 3.1.8 RF Shield
      9. 3.1.9 I/O Pins Drive Strength
    2. 3.2 Bootloader Pins
    3. 3.3 AUX Pins
      1. 3.3.1 Reference
      2. 3.3.2 CC26x2/CC13x2 AUX Pins
      3. 3.3.3 CC26x0/CC13x0 AUX Pins
    4. 3.4 JTAG Pins
  7. 4 PCB Layout
    1. 4.1  Board Stack-Up
    2. 4.2  Balun - Sub-1GHz
    3. 4.3  Balun - 2.4GHz
      1. 4.3.1 Recommended Layout and Considerations for 20dBm
    4. 4.4  LC Filter
    5. 4.5  Decoupling Capacitors
    6. 4.6  Placement of Crystal Load Capacitors
    7. 4.7  Current Return Path
    8. 4.8  DC/DC Regulator
    9. 4.9  Antenna Matching Components
    10. 4.10 Transmission Lines
    11. 4.11 Electromagnetic Simulation
  8. 5 Antenna
    1. 5.1 Single-Band Antenna
    2. 5.2 Dual-Band Antenna
      1. 5.2.1 Dual-Band Antenna Match Example: 863-928 MHz and 2.4 GHz
      2. 5.2.2 Dual-Band Antenna Match: 433-510MHz and 2.4GHz
  9. 6 Crystal Tuning
    1. 6.1 CC13xx/CC26xx Crystal Oscillators
    2. 6.2 Crystal Selection
    3. 6.3 Tuning the LF Crystal Oscillator
    4. 6.4 Tuning the HF Oscillator
  10. 7 TCXO Support
    1. 7.1 Hardware
    2. 7.2 Software
    3. 7.3 Example: Usage of TCXO on CC1312R Launchpad
  11. 8 Integrated Passive Component (IPC)
  12. 9 Optimum Load Impedance
  13. 10PA Table
  14. 11Power Supply Configuration
    1. 11.1 Introduction
    2. 11.2 DC/DC Converter Mode
    3. 11.3 Global LDO Mode
    4. 11.4 External Regulator Mode
  15. 12Board Bring-Up
    1. 12.1 Power On
    2. 12.2 RF Test: SmartRF Studio
    3. 12.3 RF Test: Conducted Measurements
      1. 12.3.1 Sensitivity
      2. 12.3.2 Output Power
    4. 12.4 Software Bring-Up
    5. 12.5 Hardware Troubleshooting
      1. 12.5.1 No Link: RF Settings
      2. 12.5.2 No Link: Frequency Offset
      3. 12.5.3 Poor Link: Antenna
      4. 12.5.4 Bluetooth Low Energy: Device Does Advertising But Cannot Connect
      5. 12.5.5 Poor Sensitivity: DCDC Layout
      6. 12.5.6 Poor Sensitivity: Background noise
      7. 12.5.7 High Sleep Power Consumption
  16. 13References
  17. 14Revision History

5.2.1 Dual-Band Antenna Match Example: 863-928 MHz and 2.4 GHz

This example is based on LaunchPad-CC1352P1.

  • Assemble LHIGH: 0Ω and CLOW : 0Ω; CHIGH: NC and LLOW : NC
  • Measure initial impedance with a network analyzer (VNA) at the low-band (868MHz) and high-band (2440MHz)
    • 868MHz: 54 + j30, VSWR: 1.78:1
    • 2.44GHz: 14 - j32, VSWR: 5.05:1 (This is not required at this stage but included for documentation purposes to note the delta).
  • Match the low-band with only the CLOW and LLOW components
    CC1354P10-6 Matching the Low-Band With CLOW: 5.6pF and LLOW: NC Figure 5-3 Matching the Low-Band With CLOW: 5.6pF and LLOW: NC
  • Confirm the low-band is matched by measuring the impedance again:
    • 868MHz: 42 + j2, VSWR: 1.18:1. Good match at the low-band
    • 2.44GHz: 16+j34, VSWR: 5.38:1
  • Match the high-band with only the CHIGH and LHIGH components
    CC1354P10-6 Matching the High-Band With an Ideal Value of LHIGH: 2.2nH and CHIGH: NC Figure 5-4 Matching the High-Band With an Ideal Value of LHIGH: 2.2nH and CHIGH: NC
  • LHIGH : 2.2nH was not sufficient when measured and a value of 3.3nH was used instead. The antenna match components are based on ideal components with no parasitics. The match is not ideal but the CHIGH component could not be used due to the impedance position in the Smith chart.
  • Measure final impedance with a network analyzer (VNA) at the low-band (868MHz) and high-band (2440MHz),
    • 868MHz: 37 + j8, VSWR: 1.36:1 Good match at the low-band
    • 2.44GHz: 16+j8, VSWR: 3.18:1 Reasonable match at the high-band but would prefer VSWR < 2.00:1; see Figure 5-5 and Figure 5-6.
      CC1354P10-6 Smith Chart With Final Match Values of LHIGH: 3.3nH and CLOW: 5.6pF Figure 5-5 Smith Chart With Final Match Values of LHIGH: 3.3nH and CLOW: 5.6pF
      CC1354P10-6 VSWR Chart With Final Match Values of LHIGH: 3.3nH and CLOW: 5.6pF Figure 5-6 VSWR Chart With Final Match Values of LHIGH: 3.3nH and CLOW: 5.6pF
  • With the matching components, the antenna match was improved by:
    • 868MHz: VSWR: 1.78:1 –> 1.36:1
    • 2.44GHz: VSWR: 5.05:1 –> 3.18:1

The example shown above used a low-band of 868MHz but a main requirement of the LaunchPad-CC1352P-1 was for good operation for the complete 863 – 928MHz band since it was important to cover both ETSI (863-870MHz) and FCC bands (902-928MHz). The antenna length on CC1352P1 has a natural resonance of approximately 900MHz with no matching components.

If the performance at 2.44GHz is more important than supporting both 868MHz and 915MHz ISM bands, then the length of the antenna can be increased so the natural resonance will be around 813MHz (2440MHz/3). This would give very good performance at 868 MHz and 2.4GHz but the 915MHz band would suffer. A common antenna match for dual-bands is a compromise of performance between the high-band and low-band.