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

2 Integrated VCO Overview

The Voltage Controlled Oscillator (VCO) converts a tuning voltage to an output frequency. It has become increasingly popular to integrate these on integrated circuits along with other functionality. To achieve good phase noise performance and wide tuning range, the VCO frequency range is typically divided into several overlapping bands. This allows the individual bands to have lower VCO gain, which corresponds to better VCO phase noise. By adding all the bands together, they can jointly create a wide tuning range. For this technique to work, a calibration routine has to be used to tell the VCO which is the proper band to use for a given frequency.