PLL basicsThe Phase-Locked Loop (PLL) is a closed loop frequency control system functioning of which is based on the phase sensitive detection of phase difference between the input signal and the output signal of the controlled oscillator (CO). From historical point of view the PLL is not a newest invention. The PLL has found use since the beginning of the 1930-ies [Bellescise, 1932].Depending on the signal type and functional elements used the PLL can be classified as analogue, discrete, digital or mixed system. Independent of this classification the PLL is a nonlinear system that has infinite periodic nonlinearity. Nevertheless, the PLL can be often analysed as a linearised system. In addition to the nonlinearity, in a lot of applications the PLL behaves also as a nonstationary system. And in noisy conditions the behavior of the PLL is stohastic, of course. In its relative complicity the PLL still remains a system not completely studied. So still some pecularities can be found out in the PLL. Only few of these to be noticed here should be the fact that even in the case of ideal components in the PLL there exists some systematic phase error [Min, 1985], that the harmonic content of the output signal has quite complicated structure [Land, 1994], and that the wide band properties of the PLL are also not so simple thing as it is sometimes taken discussing the matter [Min and Männama, 1996]. In applications the PLL system is often used in combination with the automatic frequency control (AFC) system and/or automatic gain (or signal level) control system. Keywords: phase difference detection, feedback system, voltage controlled oscillator (VCO), current controlled oscillator (CCO), frequency control, synchronisation, nonlinear system, carrier-operating system (servosystem), accuracy, dynamics, noise immunity. [Back to the beginning] |
Applications:lock-in measurement (equipment);frequency synthesi(zer)s; radio engineering; telecommunication; motor/drive speed/position control. [Back to the beginning] |
The PLL-people in the ELIN, TTU (or the PLL-Workgroup).Mart Min, Professor, PhD.Raul Land, Researcher, MSc. Jaak Tammemägi, Doctoral student, MSc. Vello Männama, Professor, PhD. Toivo Paavle, Researcher, Dipl.Eng. (Tallinn). [Back to the beginning] |
Latest and running projects connected with the PLL topic:MCCC (Measurement x Computation x Communication x Control) Synergy -Integration of Measurement, Computation, Communication and Control in electrically and informatically unified systems. Grant of the Estonian Science Foundation, No. 2847 (1997-2000). Methods and means for designing of noise-proof and speed-optimized precision tracking systems and devices/systems based on them. Grant of the Estonian Science Foundation, No. 573 (1994-1996). Methods and means for designing of optimal phase-locked loops and precision lock-in instruments. Grant of the Estonian Science Foundation, No. 126 (1993). For more information please see the PLL-Workgroup's Page. [Back to the beginning] |
A selection of the PLL related publications
M.Min and V.Männama, |
PLL Related WWW-sites:Integrated Circuit PLLs
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A short bibliography on the PLL topicsH.Meyr and G.AscheidSynchronization in Digital Communications. Volume 1. Phase-, Frequency-Locked Loops, and Amplitude Control. Wiley, 1990. A.Blanchard Phaselock loop. N.Y., John Wiley and Sons, 1976. J.B.Encinas Systémes á verrouillage de phase (P.L.L.). Masson, Paris, 1989. English version: Phase Locked Loops. Chapman & Hall, 1993. M.Girard Boucles á Verouillage de Phase. McGraw-Hill, 1988 and 199_, Ediscience, Paris, 1993 (troisiéme tirage, 316 pp. (en franc,aise). J.Smith Modern Communication Circuits. McGraw-Hill, 1986. R.Best Phase-Locked Loops, Theory, Design and Applications. McGraw-Hill, New York, 1984. Second Edition - 1993, 386 pp., 38 refs., ISBN 0-07-911386-9. U.L.Rohde Digital PLL Frequency Synthesizers. Prentice-Hall, London, 1983. F.M.Gardner Phaselock Techniques. Wiley, New York, 1981. H.L.Krauss and C.W.Bostian Solid State Radio Engineering. Wiley, New York, 1980. V.V.Shakhgildyan and L.N.Belyustina (Eds.) Phase Synchronization. Svyaz, Moscow, 1975 (in Russian) V.F.Kroupa Frequency Synthesis. Wiley, New York, 1973. V.V.Shakhgildyan and V.V.Lyakhovkin Automatic Phase Synchronization Systems. Svyaz, Moscow, 1972 (the 2nd ed.) (in Russian) W.C.Lindsey Synchronization System in Communication and Control. Prentice Hall, Englewood Cliffs, NJ, 1972. A.J.Viterby Principles of Coherent Communication. McGraw-Hill, New York, 1966. H. de Bellescise La réception synchrone. - Onde Electrique, vol.11, 1932. [Back to the beginning] |