Rohm Co., Ltd.

Koji Nishikawa

Hiroyuki Funahashi

Keisuke Kadowaki

Tomoyuki Miki

Ayumu Ibusuki

Makoto Hiraga

A multiphase DC/DC converter according to the present invention includes: a plurality of DC/DC converters whose outputs are connected in common to supply electric power to a load; a load state detection portion which detects a state of the load connected to the plurality of DC/DC converters and outputs a detection result; and a control circuit which drives each of the plurality of DC/DC converters based on outputs from the plurality of DC/DC converters, and based on an output from the load state detection portion, drives the plurality of DC/DC converters with output phases of the plurality of DC/DC converters deviated from each other or with the output phases of the plurality of DC/DC converters aligned with each other.

Multiphase DC/DC converter with output phases deviated from or aligned with each other and driven with fixed on time

By inputting differential signals to transistors Trto Trand Trto Tr, an addition operation is performed on the four differential signals, and a filter operation is performed by a capacitor Cand resistors Rand R. An offset of a signal obtained as a result of an addition operation performed on the four differential signals is removed by transistors Trand Tr

Arithmetic processing circuit unit and disc device

A waveform equalizer includes: a calculation circuit () that permits free setting of the boost factor by which the gain, in a predetermined frequency range, for the input signal by varying the boost factor; and an all-pass filter () that is connected to the stage preceding or following the calculation circuit, that has a first conductance amplifier and a second conductance amplifier, and that adjusts and thereby corrects the group delay characteristic of the input signal by varying the conductance of at least one of the first and second conductance amplifiers.

Waveform equalizer and information reproducing apparatus therewith

A signal generating circuit of the invention includes a current polarity switch circuit that receives an output current of a light-sensitive element and outputs a current of which the direction the polarity switch circuit keeps constant regardless of the direction of the received current, a current-to-voltage conversion circuit that converts the current outputted from the current polarity switch circuit into a voltage, and a signal processing circuit that receives the voltage outputted from the current-voltage conversion circuit to generate a signal based on the received voltage. Thus, the signal based on the received current signal can be generated regardless of the direction of the received current signal.

Signal generating circuit and optical pickup device provided therewith

An automatic time constant adjustment circuit has an error detection circuit and a variable time constant circuit. The error detection circuit detects, based on the resistance of an error reference resistor and the capacitance of an error reference capacitor provided therein, a resistance/capacitance error resulting from a variation attributable to an IC process, and then outputs a control signal corresponding to the resistance/capacitance error. The variable time constant circuit includes a resistance portion, a capacitance portion, and a switch portion. The resistance portion is build with one or more resistors. The capacitance portion is build with one or more capacitors. The switch portion sets the time constant of the variable time constant circuit according to the resistance/capacitance error by connecting together one of the resistors of the resistor portion and one of the capacitors of the capacitor portion according to the control signal.

Automatic time constant adjustment circuit

In a motor rotation rate detecting circuit incorporating a conventional differentiating circuit, raising the upper limit of the differentiating operation frequency of the differentiating circuit to cope with an increased range of the motor rotation rate causes the differentiating circuit to amplify high-frequency noise when the motor is rotating at a low rate. To solve this problem, a motor rotation rate detecting circuit embodying the invention incorporates a differentiating circuit that produces a rotation rate detection signal by differentiating a plurality of alternating signals having different phases that are output according to the rotation position of the motor, and the frequency response of the differentiating operation of the differentiating circuit is switchable according to the voltage of the rotation rate detection signal.

Growing community of inventors

Kyoto, Japan

Koji Nishikawa