PHASE FREQUENCY SYNCHRONIZING CIRCUIT, SYNCHRONISM JUDGING CIRCUIT AND PHOTO-DETECTOR

Japanese Patent JP3799357

B2

PROBLEM TO BE SOLVED: To provide a phase frequency synchronizing circuit for shortening the time from an asynchronous state to synchronism without unstably operating the phase frequency synchronizing circuit when switching from a frequency-locked loop to a phase-locked loop.
SOLUTION: The phase frequency synchronizing circuit is composed of a phase comparator 10 for outputting a voltage corresponding to a phase difference of a clock with an input signal as a reference, a frequency comparator 20 for judging a level of a frequency of a clock with a transmission rate of the input signal as a reference and outputting a binary signal, a synchronism discriminator 30 for judging synchronism of a phase and a frequency, a first switch which receives an output of the phase comparator 10, is closed when the synchronism discriminator 30 discriminates synchronism and is opened when the asynchronous state is judged, a second switch which receives an output of the frequency comparator 20, is opened when the synchronism discriminator 30 judges synchronism and is closed when the asynchronous state is judged, a loop filter 40 which receives an output of the first switch and an output of the second switch, and a voltage controlled oscillator 50 which oscillates on the basis of an output of the loop filter 40.

Atsushi Hasegawa
Tetsuya Aoki
Takeshi Yamashita

JP2004110644A

July 19, 2006

April 05, 2004

Click for automatic bibliography generation  

Japan Opnext Co., Ltd.

H03L7/095; H03L7/087; H03L7/113; H04B10/40; H04B10/50; H04B10/524; H04B10/58; H04B10/60; H04L7/033; (IPC1-7): H03L7/095; H04L7/033

JP3048578A
JP6104748A
JP3297221A
JP52100808A
JP60098726A
JP8163053A

Yasuo Sakuta

Previous Patent: SOLUTION CONCENTRATION METHOD AND CONCENTRATION APPARATUS

Next Patent: REPRODUCTION DEVICE, REPRODUCTION METHOD, AND PROGRAM