PLL CONTROLLER, PLL CONTROL METHOD AND LIMITER

摘要

PROBLEM TO BE SOLVED: To prevent the occurrence of a temporary stop of an output of a voltage controlled oscillator due to a rapid change in a level of a control signal given to the voltage controlled oscillator with respect to the control method for a phase locked loop PLL in a transmitter such as a MODEM. SOLUTION: The output terminal of a PLL section 24 is provided with a limiter 29 that limits an output level of the PLL section 24 and an output of the limiter 29 is given to a voltage controlled oscillator VCXO 27. The limiter 29 obtains a difference between its input signal and its output signal and limits a change in an output of the limiter 29 to a limit value when the difference exceeds a predetermined limit. The limier 29 uses an output change for the difference when the difference does not exceed the limit.