Apparatus For Lock Detection Suitable For Fractional-N Frequency Synthesizer and Method Thereof

Disclosed are an apparatus for lock detection suitable for a fractional-N frequency synthesizer and a method thereof. The lock detector for use in the fractional-N frequency synthesizer includes a delay unit delaying an N-divider output frequency clock based on an output value of a fraction ratio modulator, a lock detection unit outputting a lock detection signal by comparing a reference frequency clock with the N-divider output frequency clock delayed by the delay unit, a counter counting the number of lock detection signals received from the lock detection unit, and a controller issuing a command to output a lock identification signal based on the number of lock detection signals counted by the counter.