MODE SWITCHING METHOD FOR PLL CIRCUIT AND MODE CONTROL CIRCUIT FOR THE PLL CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a mode switching method of a PLL circuit with a high- speed mode and a normal mode which realizes high-speed lockup and to provide a mode control circuit for the PLL circuit. SOLUTION: A state detection circuit 40 outputs a mode switching signal CS latching a lock detection signal S4 on the basis of the internal state signals RS, MS, clock signals RCK, MCK of a reference counter 22 and a main counter 24, and the pulse signals UP, DOWN of a phase comparator 23.