In 1981, famous engineer William F. Egan conjectured that a higher-order type 2 PLL with an infinite hold-in range also has an infinite pull-in range, and supported his conjecture with some third-order PLL implementations. Although it is known that for the second-order type 2 PLLs the hold-in range and the pull-in range are both infinite, the present paper shows that the Egan conjecture may be not valid in general. We provide an implementation of the third-order type 2 PLL, which has an infinite hold-in range and experiences stable oscillations. This implementation and the Egan conjecture naturally pose a problem, which we will call the Egan problem: to determine a class of type 2 PLLs for which an infinite hold-in range implies an infinite pull-in range. Using the direct Lyapunov method for the cylindrical phase space we suggest a sufficient condition of the pull-in range infiniteness, which provides a solution to the Egan problem.

Original languageEnglish
Article number9258948
Pages (from-to)1467-1471
Number of pages5
JournalIEEE Transactions on Circuits and Systems II: Express Briefs
Volume68
Issue number4
DOIs
StatePublished - Apr 2021

    Scopus subject areas

  • Electrical and Electronic Engineering

    Research areas

  • describing function, Detectors, Egan conjecture, Egan problem on the pull-in range, Frequency control, Gardner problem on the lock-in range, global stability, harmonic balance method., hold-in range, Lyapunov functions, Lyapunov methods, nonlinear analysis, Phase locked loops, Phase-locked loop, PLL, Stationary state, Transfer functions, type 2, type II, Voltage-controlled oscillators, harmonic balance method, non-linear analysis

ID: 73410588