Fuzzy Controlled Phase Locked Loop (FCPLL)

Abstract

Phase locked loop (PLL) operates on the principle of feed back control, except that the feed back quantity is not the amplitude but the phase of the sinusoidal input signal. If the input sinusoid is noisy, the PLL not only tracks the sinusoidal signal, but also cleans it up. The PLL can be used as an FM demodulator and frequency synthesizer. The PLL, being a relatively inexpensive integrated circuit, has become one of the most frequently used communication circuit. PLL is also used in space-vehicle-to-earth data links where there is a premium on transmitter weight or where the loss along the transmission path is very large. A classic PLL consists of a voltage controlled oscillator (VCO), a multiplier serving as a phase detector (PD) or phase comparator and a loop filter. The VCO adjusts its own frequency until it is equal to that of the input sinusoidal signal such that the frequency and phase of the two signals are in synchronism (except for a possible difference of a constant phase). This paper deals with some aspects of design and analysis of Fuzzy-Controlled PLL. It considers control of the loop gain by studying the phase variation between the two signals. The fuzzification deals with triangular membership functions for phase angle of the input signal and the voltage V_dc of the output signal. Fuzzy inference is drawn using IF-THEN rules. Defuzzification is carried out using height defuzzification method. We report improvement in S/N ratio and the lock in range frequency of a fuzzy controlled PLL as compared with that of classic PLL.

Additional information

Notes on contributors

A B Kulkarni

Ashok Balkrishna Kulkarni born in 1948 at Bijapur (Karnataka, India) obtained his BSc (Agra University), MSc (Karnatak University) and PhD (Kurukshetra University) degrees in 1966, 1969 and 1979 respectively. He was research fellow of CSIR, New Delhi and Department of Atomic Energy, Mumbai. He worked in the areas of Nuclear Reaction Mechanisms, Superionic Conductors, Microwave Antennas and Materials and PC-based Instrumentation. He worked as Lecturer (1972–83), Reader in Physics (1983–87) and Professor of Applied Electronics (1987-till date). Presently, he is Professor and Chairman, Department of Applied Electronics, Gulbarga University, Gulbarga (Karnataka, India). His current interests are Synthesis of chiral materials for chirodome applications, chiropatch antennas and their arrays and Design and development of Fuzzy Logic Controllers for Process Control Instrumentation. He has completed a number of research projects funded by the UGC, DRDO and AICTE. He is Fellow of IETE.

S V Halse

S V Halse born in 1964 at Bhalki (Karnataka), obtained his MSc (Applied Electronics), MPhil (Applied Electronics) degree from Gulbarga University, Gulbarga in First class, in the year 1987 and 1997 respectively. He also obtained PG diploma in Electronics Data Processing and Computer Management from Bhartiya Vidyapeeth, Mumbai. He is presently working for his PhD degree. His area of interest is Fuzzy logic controllers and Digital communication. He is Head of the Dept of Electronics in Sharanbasaveshwar College of Science, Gulbarga.

S R Sawant

Shashikant R Sawant did his MSc and PhD. He is currently working on Fuzzy Logic and its applications to design and control. He has so far guided successfully 8 students for PhD, 9 students for MPhil and 2 students for MSc PPPR. He obtained his PhD in 1982 and has completed one UGC project on development of high permeability materials. He has worked as Dean of faculty of Science, Chairman BOS in Electronics, member of Faculty of Science and Academic Council of Shivaji University, Kolhapur. So far he has published 72 research papers in journals and presented 26 papers in conferences. He has experience of teaching Electronics course to MSc, MPhil and Engineering students. At present he is working as Head of Electronics Department, Shivaji University, Kolhapur.

R R Mudholkar

Ravindra R Mudholkar received the BSc degree and MSc in physics with electronics as a special subject in 1981 and 1984 respectively from Karnatak University, Dharwad. He has been awarded MPhil degree in Electronics in 1996 by Shivaji University, Kolhapur. Currently he is working as a lecturer in electronics at Vivekanand Science College, Kolhapur. He is presently engaged with research on the usage of Fuzzy Logic in modeling the design aspects of transformer at the Department of Electronics, Shivaji University, Kolhapur. His research interests include the implementation of Fuzzy Logic in modeling the vague concepts involved in the field of electronics system design and simulation of fuzzy based design algorithms.