SNAU278 July   2022

 

  1.   Abstract
  2.   Trademarks
  3. 1LMX2594PSEVM Evaluation Module
    1. 1.1 Evaluation Module Contents
    2. 1.2 Evaluation Setup Requirement
    3. 1.3 Resources
  4. 2Setup
    1. 2.1 Connection Diagram
    2. 2.2 Power Supply
    3. 2.3 Reference Clock
    4. 2.4 SYNC Input
    5. 2.5 RF Output
    6. 2.6 Programming
    7. 2.7 Evaluation Software
  5. 3Typical Measurement
    1. 3.1 Category 3 Synchronization
    2. 3.2 Phase Noise Improvement
  6. 4Schematic
  7. 5PCB Layout and Layer Stack-up
    1. 5.1 PCB Layer Stack-Up
    2. 5.2 PCB Layout
  8. 6Bill of Materials
  9. 7EVM Modification
  10. 8Troubleshooting Guide
  11. 9Reference PRO
    1. 9.1 Output Frequency Selection
    2. 9.2 Output Format Selection
    3. 9.3 Typical Output Characteristics
    4. 9.4 Firmware Update

3.2 Phase Noise Improvement

By combining the output of two synthesizers that are in-phase, a theoretical 3-dB phase noise benefit is possible due to the output power being 6-dB higher while the noise power is only 3-dB higher.

To measure the combined phase noise, some modification to the EVM is needed. See Section 7 for details.

In Figure 3-5, the blue trace shown the phase noise of individual LMX2594 device while the black trace respresented the phase noise of the combined signal.

GUID-20220721-SS0I-DBBP-JQCX-VWRKQV2D4RLB-low.pngFigure 3-5 Combined Phase Noise