SNAA342 September   2020 LMX2820

 

  1.   Trademarks
  2. 1 Overview of Frequency Hopping
  3. 2 Integrated VCO Overview
    1. 2.1 Integrated Silicon VCO Structure
    2. 2.2 Robustness and Consistency of VCO Calibration
  4. 3Components of Synthesizer Lock Time
    1. 3.1 Write Time
    2. 3.2 VCO Calibration Time
    3. 3.3 Analog Settling Time
  5. 4Improving VCO Calibration Time With the LMX2820
    1. 4.1 Improving LMX2820 VCO Calibration With Partial Assist
    2. 4.2 Full Assist Method of Improving VCO Calibration Time
    3. 4.3 Instant Calibration – The Ultimate to Blazing-Fast VCO Calibration
  6. 5Conclusion
  7. 6References

3 Components of Synthesizer Lock Time

The time that it takes a synthesizer to change from one frequency to another is composed of three major components. The first component is the time that it actually takes to tell the synthesizer to change the frequency. This is typically done through a serial programming bus. The second component is the VCO calibration time, which is the time it takes for the VCO to find the correct settings (VCO_CORE, VCO_CAPCODE, VCO_DACISET). After the VCO calibration is finished, there will be some frequency error (Δf). The final component is the analog settle time, which is the time it takes for this final frequency error after the VCO calibration to settle within a given tolerance.