Method, system, apparatus, and program for measuring the damping factor of an Nth order phase locked loop (PLL)
View Patent ↗A method for measuring the damping factor of an N th -order phase-locked loop, wherein N>1, and a system, apparatus, and program that operate in accordance with the method. The method includes applying a modulation source at an input to the phase-locked loop. The method also includes measuring the output response to various levels of frequency modulation, measuring the −3 dB cutoff frequency of the phase-locked loop, and measuring the peak frequency of the phase-locked loop. The method further includes calculating the damping factor of the phase-locked loop as a function of the −3 dB cutoff frequency and the peak frequency.
1. A method for measuring the damping factor of an N th -order phase-locked loop, wherein N>1, comprising the steps of:
applying a modulation source at an input to the phase-locked loop;
measuring an output response to various levels of frequency modulation;
measuring a −3 dB cutoff frequency of the phase-locked loop;
measuring a peak frequency of the phase-locked loop;
calculating the damping factor of the phase-locked loop as a function of the −3 dB cutoff frequency and the peak frequency.
2. The method of claim 1 , wherein N=2.
3. The method of claim 1 , further comprising the step of providing a test circuit for measuring a transfer function which describes the frequency-domain behavior of the phase-locked loop.
4. The method of claim 3 , wherein the test circuit comprises a sinewave generator, a signal generator, and an oscilloscope.
5. The method of claim 1 , wherein the phase-locked loop comprises a phase detector, a loop filter, and a voltage-controlled oscillator.
6. The method of claim 5 , wherein the loop filter comprises a low-pass filter.
7. A system for measuring the damping factor of an N th -order phase-locked loop, wherein N>1, comprising:
a modulation source adapted to apply an input to the phase-locked loop;
at least one unit adapted to generate an output response to various levels of frequency modulation and calculate the damping factor of the phase-locked loop as a function of a −3 dB cutoff frequency and a peak frequency of the generated output response.
8. The system of claim 7 , wherein N=2.
9. The system of claim 7 , further comprising a −3 dB cutoff frequency measuring unit adapted to measure the −3 dB cutoff frequency of the phase-locked loop.
10. The system of claim 7 , further comprising a peak frequency measuring unit adapted to measure the peak frequency of the phase-locked loop.
11. The system of claim 7 , wherein the at least one unit is a test unit comprising a sinewave generator, a signal generator, and an oscilloscope.
12. The system of claim 7 , wherein the phase-locked loop comprises a phase detector, a loop filter, and a voltage-controlled oscillator.
13. The system of claim 12 , wherein the loop filter comprises a low-pass filter.
14. A system for measuring the damping factor of an N th -order phase-locked loop, wherein N>1, comprising:
a modulation unit, adapted to apply an input to the phase-locked loop;
a first measuring unit, adapted to measure an output response to various levels of frequency modulation;
a second measuring unit, adapted to measure a −3 dB cutoff frequency of the phase-locked loop;
a third measuring unit, adapted to measure a peak frequency of the phase-locked loop; and
a calculating unit, adapted to calculate the damping factor of the phase-locked loop as a function of the −3 dB cutoff frequency and the peak frequency.
15. The system of claim 14 , wherein N=2.
16. The system of claim 14 , wherein the at least one unit is a test unit comprising a sinewave generator, a signal generator, and an oscilloscope.
17. The system of claim 14 , wherein the phase-locked loop comprises a phase detector, a loop filter, and a voltage-controlled oscillator.
18. The system of claim 17 , wherein the loop filter comprises a low-pass filter.