Synchronization circuit and method relating to the synchronization circuit

A synchronization circuit comprising:

• a first delay circuit configured to delay a first clock signal by a varied delay time according to a first delay control signal, and configured to output a delayed signal of the first delay circuit;
• a second delay circuit configured to delay the output signal of the first delay circuit by a varied delay time according to a second delay control signal, and configured to output a delayed signal of the second delay circuit as a second clock signal;
• a phase detector configured to generate a phase detection signal by detecting a phase difference between the first and second clock signals;
• a skip period information generation circuit configured to generate skip period information by performing a phase unstable period detection operation according to the phase detection signal;
• and
• a delay control signal generation circuit configured to adjust the second delay control signal according to the skip period information, such that a phase unstable period, detected in the phase unstable period detection operation, is skipped in a delay time tuning operation.

A method for operating a synchronization circuit, the method comprising:

• determining whether the current operation state of the synchronization circuit is a power-up sequence;
• performing a phase unstable period detection operation by controlling a second delay circuit when the current operation state is the power-up sequence;
• storing the number of unit delays of the second delay circuit corresponding to a phase unstable period, detected in the phase unstable period detection operation, as skip period information;
• and
• performing a delay time tuning operation by controlling a first delay circuit and the second delay circuit when the current operation state is not the power-up sequence,
• wherein the second delay circuit is controlled according to the skip period information such that the phase unstable period is skipped when performing the delay time tuning operation.