SWRA834 May   2025 CC2340R5 , CC2340R5-Q1 , CC2744R7-Q1 , CC2745P10-Q1 , CC2745R10-Q1 , CC2745R7-Q1 , CC2755R10

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 Reference Designs
    1. 2.1 LP-EM-CC2340R53
    2. 2.2 LP-EM-CC2340R5
    3. 2.3 LP-EM-CC2340R5-Q1
    4. 2.4 LP-EM-CC2340R5-RGE-4x4-IS24
    5. 2.5 LP-EM-CC2745R10-Q1
  6. 3 Schematic
    1. 3.1 Schematic Overview
      1. 3.1.1 48MHz Crystal
      2. 3.1.2 32.768kHz Crystal
      3. 3.1.3 Filter
      4. 3.1.4 Decoupling Capacitors
      5. 3.1.5 Antenna Components
      6. 3.1.6 RF Shield
    2. 3.2 I/O Pins Drive Strength
    3. 3.3 Bootloader Pins
    4. 3.4 Serial Wire Debug (SWD) Pins
  7. 4 PCB Layout
    1. 4.1 Board Stack-Up
    2. 4.2 LC Filter
    3. 4.3 Decoupling Capacitors
    4. 4.4 Placement of Crystal Load Capacitors
    5. 4.5 Current Return Path
    6. 4.6 DC/DC Regulator
    7. 4.7 Antenna Matching Components
    8. 4.8 Transmission Lines
    9. 4.9 Electromagnetic Simulation
  8. 5 Antenna
  9. 6 Crystal Tuning
    1. 6.1 CC23xx and CC27xx Crystal Oscillators
    2. 6.2 Crystal Selection
    3. 6.3 Tuning the LF Crystal Oscillator
    4. 6.4 Tuning the HF Crystal Oscillator
  10. 7 Optimum Load Impedance
  11. 8 PA Table
  12. 9 Power Supply Configuration
    1. 9.1 Introduction to Power Supply
    2. 9.2 DC/DC Converter Mode
    3. 9.3 Global LDO Mode
  13. 10Board Bring-Up
    1. 10.1 Power On
    2. 10.2 RF Test: SmartRF Studio
    3. 10.3 RF Test: Conducted Measurements
      1. 10.3.1 Sensitivity
      2. 10.3.2 Output Power
    4. 10.4 Hardware Troubleshooting
      1. 10.4.1 No Link: RF Settings
      2. 10.4.2 No Link: Frequency Offset
      3. 10.4.3 Poor Link: Antenna
      4. 10.4.4 Bluetooth Low Energy: Device Does Advertising But Cannot Connect
      5. 10.4.5 Poor Sensitivity: Background Noise
      6. 10.4.6 High Sleep Power Consumption
  14. 11Summary
  15. 12References

7 Optimum Load Impedance

The matching environment for optimum performance is determined through a combination of load- and source-pull measurements, given as a terminating load or source impedance. This requires comprehensive measurements to characterize the nonlinear response of the RF front-end.

The parameters considered include:

  • Transmit output power
  • Transmit efficiency
  • Transmit harmonic power levels
  • Transmit output spectrum
  • Receiver sensitivity

The operating conditions considered include:

  • Frequency
  • Voltage range
  • Transmit power settings
  • Package parasitics

Additionally, the effect of temperature variation on transmit/receive performance must also be considered.

These impedance locations are typically located in different regions of the Smith chart and a design space giving the best tradeoff between transmit and receive performance is identified for a given set of operating conditions.

The identified target impedances can be highly dependent on the power and ground planes of the application circuit and accurate measurement system calibration, along with the effects of differential and common current components due to the PCB layout. While detailed simulations of the PCB using EDA tools can add confidence to a design, simulation inaccuracies (such as component models) add additional errors that can be difficult to account for.

Due to the number of parameters that must be considered and amount of testing required for a robust design, TI recommends to follow the reference design.