Lock detector and delay-locked loop having the same

A lock detector of a delay-locked loop (DLL) includes a lock detection unit and a bias unit. The lock detection unit generates a charge control signal based on a reference current received from an external source and a plurality of delay signals received from an external voltage-controlled delay line (VCDL), controls a charge current based on the charge control signal, and detects a lock state of the DLL based on a voltage that varies depending on the charge current. The bias unit provides a bias voltage for controlling a magnitude of the charge current. Therefore, the lock detector stably detects a lock state of the DLL.