Skhynix Inc.

Hynix Semiconductor Inc.

Joo-Hwan Cho

Hae-Rang Choi

Kwang-Jin Na

Kwan-Dong Kim

Yong-Suk Joo

A phase-locked loop includes a phase detection unit configured to compare the phase of a feedback clock with the phase of an input clock, a clock generation unit configured to adjust the frequency of a first clock based on a result of the comparison of the phase detection unit, a first division unit configured to generate an output clock by dividing the first clock at a first division ratio in test mode and generate the output clock by dividing the first clock at a second division ratio that is lower than the first division ratio in normal mode, and a second division unit configured to generate the feedback clock by dividing the output clock.

Phase-locked loop and integrated circuit chip including the same, and test system including the integrated circuit chip

A semiconductor memory device includes a clock input unit configured to receive a first clock and a second clock from the external. The memory device further includes a frequency conversion unit configured to convert a frequency of the second clock so that the frequency of the second clock becomes identical to a frequency of the first clock, a phase comparison unit configured to compare a phase of the first clock with that of a clock outputted from the frequency conversion unit, and output a comparison signal corresponding to the comparison result, a logic level change unit configured to change a logic level of a training information signal when a logic level of the comparison signal is fixed for a given time after being changed, and a signal transfer unit configured to transfer the training information signal to the external.

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Gyeonggi-do, South Korea

Joo-Hwan Cho