Fujitsu Corporation

Joshua Liang

Hirotaka Tamura

Ali Sheikholeslami

Sanroku Tsukamoto

Hisakatsu Yamaguchi

Yuuki Ogata

A jitter measurement circuit includes an addition circuit to add a digital rectangular signal to an adjustment signal generated by a circuit that generates a first error signal based on a phase difference between a first clock signal or a data signal on which the first clock signal is superimposed and a second clock signal and generates the adjustment signal by filtering the first error signal, and a calculation circuit to calculate a first correlation value for representing an autocorrelation of the first error signal when the rectangular signal is not added to the adjustment signal, and a second correlation value for representing the autocorrelation when the rectangular signal is added to the adjustment signal, based on the first error signal and a second error signal obtained by delaying the first error signal by a variable delay amount, and output the first correlation value and the second correlation value.

Jitter measurement circuit and jitter measurement system

A serial-parallel conversion circuit includes: a phase detector that outputs a first phase detection signal indicating whether a phase of a clock signal is advance or behind, a signal amplifying circuit that amplifies the first phase detection signal with a gain so as to output a second phase detection signal; a control loop that adjusts the phase of the clock signal based on the second phase detection signal; an autocorrelation circuit that generates an autocorrelation value based on the first phase detection signal and a set delay amount, and outputs an autocorrelation signal indicating the autocorrelation value; a gain adjusting circuit that adjusts the gain in such a manner that the autocorrelation value matches a target correlation value; and a delay-amount determination circuit that sets a delay amount corresponding to a peak value of an obtained autocorrelation value obtained when the autocorrelation value changes in an oscillatory manner.

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Toronto, Canada

Joshua Liang