SNAA366 October   2022 LMX1204

 

  1.   Abstract
  2.   Trademarks
  3. 1Introduction
    1. 1.1 Basic Clock Distribution System
    2. 1.2 Pre-multiplier Stage
  4. 2Low-Frequency Reference
    1. 2.1 Pre-multiplier Stage
    2. 2.2 LMX1204 Multiplier Stage
    3. 2.3 LMX1204 Multiplier vs RF Synthesizer
  5. 3Real-World Application With AFE7950 RF Sampling Transceiver
    1. 3.1 AFE7950 Clocking Measurement Setup
    2. 3.2 AFE7950 Clocking Measurement Results
  6. 4Conclusion

1.1 Basic Clock Distribution System

The LMX1204 includes a 2 ×, 3 ×, or 4 × multiplier option. The caveat is that the output frequency must be within 3.2 GHz to 6.4 GHz. The goal is to generate a 5898.24-MHz clock from a 491.52-MHz reference. Multiplying up from 491.52 MHz directly with the LMX1204 is not possible since the first multiply stage does not satisfy the output frequency requirement. As such, a pre-multiplier stage is needed to get the input frequency within the proper range.