SNAA393 January   2024 LMK6C , LMK6D , LMK6H , LMK6P

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 Why use a Phase Noise Analyzer?
  5. 2Understanding Phase Noise Plots
  6. 3Phase Noise Analyzer Measurement Settings
    1. 3.1 Start or Stop Frequency
    2. 3.2 Averaging and Correlation
    3. 3.3 Persistence
    4. 3.4 Spurious View Modes
    5. 3.5 Other Settings
  7. 4Hardware Setup for Different Clocking Formats
    1. 4.1 LVCMOS
    2. 4.2 LVDS
    3. 4.3 LVPECL/HCSL
    4. 4.4 Balun Recommendations
  8. 5Typical Measurements with Different Termination Schemes
    1. 5.1 LVCMOS
    2. 5.2 LVDS
    3. 5.3 LVPECL
    4. 5.4 HCSL
  9. 6Summary
  10. 7References

4.4 Balun Recommendations

To maintain signal integrity, it is recommended to use a balun with a Voltage Standing Wave Ratio (VSWR) less than 2 and a phase imbalance of less than 8°.

A hybrid coupler can also be used to convert differential signals to single-ended and is commonly used for measurements of TI clocking devices. Hybrid couplers typically have less insertion loss compared to baluns which results in better noise floor performance. Some hybrid couplers that TI uses include the MACOM H-183-4, Mini-Circuits ZFSCJ-2-1+, and Mini-Circuits ZFSCJ-2-4+.