FREQUENCY DETECTING APPARATUS FOR GENERATING STABLE CLOCKS SYNCHRONIZED WITH INPUT SIGNAL AND METHOD THEREOF, AND SIGNAL AMPLIFYING FILTER USED FOR THE SAME

摘要

PURPOSE: A frequency detecting apparatus for generating clocks of an optical disk and a method thereof are provided to stably obtain a frequency error even if the quality of a reproduced signal is bad and even if a frequency difference between an input signal and an oscillation frequency is big, thereby improving the stability of a PLL(Phase Locked Loop) circuit. CONSTITUTION: A signal amplifying filter(410) filters radio frequency components of a predetermined input signal, and amplifies the filtered radio frequency components. A frequency detector(420) receives the input signal of which the radio frequency components are amplified and a predetermined clock signal to detect a frequency difference between the input signal and the clock signal, and to generate a control voltage corresponding to the frequency difference.