SNAA393 January   2024 LMK6H

 

  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

4.3 LVPECL/HCSL

If a balun is unavailable, the measurements can be taken single-ended. Note that for single-ended measurements, it is important to correctly terminate the unused end of the output as shown in Figure 4-5 to make sure proper loading on the output driver. When taking single-ended measurements without a balun, there can also be some degradation in phase noise performance due to a decrease in signal power and lack of common-mode noise rejection.

GUID-20230927-SS0I-XWVK-P0X2-4L3LGPLZRW6D-low.svg Figure 4-4 Recommended LVPECL/HCSL Termination Scheme for Phase Noise Measurements
GUID-20231013-SS0I-J37M-J41L-3ZFJ3XL7W2X4-low.svg Figure 4-5 Alternative LVPECL/HCSL Termination Scheme for Phase Noise Measurements (Single-Ended)
Table 4-1 Source Termination Resistor Values for LMK6P
Supply Voltage (V) Rp (Ω)
3.3 207.5
2.5 112.5
1.8 83.3
Table 4-2 Source Termination Resistor Values for LMK6H
Supply Voltage (V) Rp (Ω)
3.3 50
2.5 50
1.8 50