Bezboruah, T: Phase-locked loop

The phase-locked loop (PLL) is a feedback control system, used to lock the output frequency and phase according to the frequency and phase of input signal. It can also be used as a frequency synthesizer for modulation and demodulation circuits. In general, PLL is used in both transmitting and receiving terminals of wireless communication systems. A nearly description of PLL appeared in the paper by Appleton in 1923. It was conceived by H. De Bellecize in 1932. Since then, it is widely used in applications involving automatic control of phase or frequency, such as applications in communications, control systems, measurements and instrumentation and in many other applications. The synchronization of horizontal and vertical scan in televisions produced the first widespread use of PLL. One of the first large-scale industrial applications of the PLL (back in the yearly 1950s) was the color sub-carrier recovery in color TV receivers. This work illustrates the modeling of high speed PLL applicable for very high frequency (VHF) communication systems. Details of theoretical estimation of the model and its simulation on MatLab Platform in behavioral level is also presented in the book.