SNAA361A april   2022  – may 2023 LMX2820

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Reference Frequency
  6. 3Standard LMX2820 Phase Noise Performance
  7. 4 Pre-multiplier Stage Performance
    1. 4.1 External VCO Loop Filter Design
    2. 4.2 Active Loop Filter Implementation
    3. 4.3 External VCO Performance Results
  8. 5External PFD Topology
    1. 5.1 External PFD Loop Filter Modification
    2. 5.2 External PFD Measurement Results
  9. 6Putting it Together in the Real World
    1. 6.1 Real-World Performance Results
    2. 6.2 Why use the Dual Approach?
  10. 7Conclusion
  11. 8Revision History

7 Conclusion

The LMX2820 is a good low-noise RF synthesizer device. Two alternative topologies provide improved performance that rival high-end test equipment: external VCO and external PFD. Combining these two approaches yields a real-world topology that provides extremely good phase noise performance while also providing flexibility to adjust the frequency output.

The improved synthesizer performance provides realizable clock and LO solutions for stringent spot noise applications in high-interference systems like wireless infrastructure transceivers and software defined radios. The excellent integrated RMS jitter performance is suitable for clock solutions in high-resolution radar systems and high-QAM rate communication systems.