Fixed-phase loop (FPL)

Luis T. Aguilar, Igor Boiko, Leonid Fridman, Rafael Iriarte

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review


There exist a number of applications in which oscillations must be produced at a certain phase shift with respect to a reference signal. Phase-lock loop (PLL) is widely used for this purpose. PLL uses a closed-loop control principle for tracking the required phase shift. Another solution, which uses an open-loop control principle for the phase angle, can be realized on the TRC considered in this book. This solution is named here a fixed-phase loop (FPL). FPL is an oscillator consisting of a TRC and a low-pass (LP) filter that generates a periodic voltage signal of the frequency corresponding to a certain specified phase lag of the LP filter. Regardless of the LP filter connected in a loop with the TRC, oscillations are always produced at the same phase lag value. Two different circuits are considered: without and with an additional integrator. The purpose of the considered self-oscillating circuit is to produce a periodic reference signal at the output of the filter with desired frequency and amplitude. Sufficient conditions for orbital asymptotic stability of the closed-loop system is verified through the Poincaré map. The two FPL circuits are illustrated by simulations and experiments.

Original languageBritish English
Title of host publicationSystems and Control
Subtitle of host publicationFoundations and Applications
Number of pages15
StatePublished - 2015

Publication series

NameSystems and Control: Foundations and Applications
ISSN (Print)2324-9749
ISSN (Electronic)2324-9757


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