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Optimisation of a parasitic deviation of a phase of PPLL of frequency synthesizers

Keywords:

G. N. Prokhladin


Noise characteristics on an exit of system of pulse-phase-locked-loop (PPLL) with a frequency divider in a feedback chain are investigated. The analysis of the given system on one of its cores, quality indicators – to a parasitic deviation of phase (PDP) of spectral density of capacity of noise in the set strip of frequencies is resulted. Influence of parameters of system on this indicator is presented. Laws of change PDP from factor of division of a divider in a feedback and an emission indicator are found out. It is shown, that system PPLL with the standard non-uniformity of the target frequency characteristic has a pass-band approximately in 5 times of less frequency of comparison. Therefore it is possible to consider such system continuous and for the analysis to use calculations for continuous structures. It is noticed, that indicator PDP on a loop exit grows in time at multiplication of indignations to a loop input in N time. At the same time, the relative factor of growth of indicator PDP for various values of emission indicator has the same character of change. The received laws allow to predict in advance possible values of indicator PDP for frequency synthesizers of (FS) with PPLL at a stage of preliminary designing of all system. It essentially simplifies a problem of a choice of the reference frequency generator and the voltage controlled oscillator, and also factors of division of a divider in a chain of feedback FS.
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