Fujitsu Corporation

Kazunori Hayami

Takao Naito

Yoshiyasu Nakashima

Yu Yonezawa

Hiroshi Nakamoto

Satoshi Yamamoto

Mitsuo Kitamura

Tatsuo Nagayoshi

Takanori Maki

Koichi Kimotsuki

Shinji Sonoda

Tetsuya Ohtani

Tatsuya Yamaguchi

A power supply apparatus includes a power supply section and a control section. The power supply section includes a first switch which performs switching of power-supply output, an inductor and a capacitor which form an LC circuit that resonates current flowing through the first switch, and a second switch which changes capacitance of the capacitor. The control section finds in advance a correspondence between a time ratio of a switching pulse of the first switch and a resonance frequency which matches an edge of a switching pulse having each time ratio, and controls switching of the second switch so as to resonate the LC circuit at a resonance frequency corresponding to a time ratio at operation time.

Power supply apparatus

An interface circuit includes a driver circuit () made up of a combination of a plurality of transistors, a calibration circuit () for performing selection of on and off of one or more of the plurality of transistors for adjusting on-resistance thereof, and a terminating resistor () that is connected to an output side of the driver circuit (). One or more of the transistors are turned on based on an output of the calibration circuit (), so that a combination resistance value of the on-resistance and the terminating resistor matches characteristic impedance of the transmission line. The driver circuit (), the calibration circuit () and the terminating resistor () are formed on the same semiconductor integrated circuit SK, and the calibration circuit () detects process variation and temperature variation of the transistor and the resistor formed on the semiconductor integrated circuit (SK).

Interface circuit and semiconductor integrated circuit

A voltage controlled oscillator circuit includes a ring oscillator including a plurality of delay circuits that are connected like a ring and a voltage to current converter circuit for controlling current flowing in the ring oscillator so as to change an oscillation frequency thereof. The voltage to current converter circuitis provided with a shunt circuit for shunting a part of current obtained by converting input voltage, and the shunted part of the current is used for controlling the current flowing in the ring oscillator.

Voltage controlled oscillator circuit with different sized shunt transistors

The present invention is directed to the provision of a wavelength division multiplexing optical transmission apparatus and, more particularly, to a wavelength division multiplexing optical transmission apparatus having high wavelength stability unaffected by the temperature characteristics, aging, etc. of an arrayed-waveguide grating (AWG) and its peripheral components. The wavelength division multiplexing optical transmission apparatus comprises: an arrayed-waveguide gratinghaving operating input/output ports and an input dummy port; a light emitting meansfor generating a pilot signal to be input to the input dummy port; a light detecting meansfor monitoring the pilot signal contained in a wavelength division multiplexed signal output from the operating output port; and a temperature control circuitfor controlling the temperature of the arrayed-waveguide grating in such a manner as to cancel the amount of wavelength fluctuation occurring in the arrayed-waveguide grating and detected by monitoring the pilot signal.

Wavelength division multiplexing optical transmission apparatus

The present invention relates to an optical transmitter and particularly to an optical transmitter including an external optical modulator such as Mach-Zehnder type optical modulator which modulates the light from a light source to output an optical signal with a drive voltage signal generated depending on an input signal According to the present invention is achieved by providing an optical modulator, which add weighting to operating point control signal in accordance with optical output level of the modulator.

Optical modulator outputting an optical signal with a drive voltage signal dependent upon an input signal

A phase shift circuit includes a first trailing-edge elongating circuit that elongates a trailing edge of each pulse of an input clock signal so as to fall gradually and outputs a first clock signal having a first elongated fall time. A signal inversion circuit inverts the first clock signal supplied from the first trailing-edge elongating circuit and outputs an inverted version of the first clock signal. A second trailing-edge elongating circuit elongates a trailing edge of each pulse of the inverted version of the first clock signal so as to fall gradually and outputs a second clock signal having a second elongated fall time. The second clock signal is an output signal of the phase shift circuit and lags behind the input clock signal by a predetermined time based on the first and second elongated fall times. The present invention further provides a repeater which uses the above-mentioned phase shift circuit.

Growing community of inventors

Fukuoka, Japan

Kazunori Hayami