JITTER DETECTING APPARATUS AND PHASE LOCKED LOOP USING THE SAME

摘要

PURPOSE: A jitter detecting apparatus is provided to detect a jitter amount using signals existing at two sampling points around an edge, from an analog-to-digital converted signal. CONSTITUTION: An edge detecting portion(200) judges symbol variation of signals at two successive sampling points from a DC offset-eliminated input signal, and outputs a before-symbol-variation signal and an after-symbol-variation signal as first and second edge signals, respectively. A comparator portion(210) compares the first and second edge signals from the edge detecting portion(200) and outputs any one of the first and second edge signals having a relatively small absolute value. A calculation portion(220) outputs a jitter value by dividing the relatively small absolute value from the comparator portion(210) by a sum of absolute values of the first and second edge signals.