Phase-locked loop is classical nonlinear control system for frequency and phase synchronization in electrical circuits. According to the Egan conjecture, the type 2 loops have an infinitely large pull-in range. This article reconsider the pull-in problem for the fourth order type 2 PLLs. The global stability domain is estimated by applying Lyapunov direct method for the cylindrical phase space. An analytical estimate of the pull-in range of the fourth-order PLL is presented for the first time in the literature. Parameters violating the pull-in conditions are determined by computer simulation. The results have revealed that stable oscillations may develop in the higher-order type 2 PLL in steady-state which is a clear counterexample to the Egan's conjecture.

Original languageEnglish
Pages (from-to)73-78
Number of pages6
JournalIFAC-PapersOnLine
Volume54
Issue number21
DOIs
StatePublished - 1 Dec 2021
Event2021 Control Conference Africa, CCA 2021 - Magaliesburg, South Africa
Duration: 7 Dec 20218 Dec 2021

    Scopus subject areas

  • Control and Systems Engineering

    Research areas

  • analog PLL, cylindrical phase space, Egan conjecture, Egan problem on the pull-in range, global stability, harmonic balance method, Lyapunov functions, nonlinear analysis, Phase-locked loop, phase-locked loop, PLL, pull-in range, type 2, type II

ID: 87582565