Nippon Telegraph and Telephone Corporation

Keiji Kishine

Jun Terada

Yusuke Ohtomo

Kazuyoshi Nishimura

Tomoaki Kawamura

Haruhiko Ichino

Minoru Togashi

A recovered clock () is generated by making the phase of a reference clock () having the same frequency as the data rate frequency of input data () match the phase of the input data (). The input data () is written in a FIFO () using the recovered clock (). For readout from the FIFO (), the FIFO () is caused to output recovered data () using the reference clock () asynchronous to the recovered clock ().

CDR circuit

A clock/data recovery circuit includes a data duty correction circuit which outputs corrected data by correcting the duty of input data in accordance with the level of a correction signal, a clock recovery circuit which generates a recovered clock in synchronism with the edge timing of the corrected data, a data decision circuit which performs data decision of the corrected data based on the recovered clock, and a data duty detection circuit which detects the duty of the corrected data based on the recovered clock and outputs the correction signal representing a duty correction amount to the data duty correction circuit.

Clock/data recovery circuit

A clock/data recovery circuit used in a receiving apparatus is provided in the circuit including: a voltage control oscillator for generating a clock signal of a frequency of 1/K of a bit rate of an input data signal; a delay circuit; a demultiplexer for demultiplexing the input data signal; a multiplexer for multiplexing the demultiplexed signals; a phase comparator for comparing phases of an output signal of the delay circuit and an output signal of the multiplexer; a lowpass filter; wherein the clock/data recovery circuit outputs the clock signal generated by the voltage control oscillator as a recovery divided clock signal, and outputs the demultiplexed signals output as recovery parallel data signals.

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Kanagawa, Japan

Keiji Kishine