Mitsubishi Denki Kabushiki Kaisha

Renesas Electronics Corporation

Renesas Technology Corp.

Mitsubishi Electric Engineering Company, Limited

Other

Renesas Technology America, Inc.

Takehiko Umeyama

Toru Takeuchi

Tsuyoshi Horiuchi

Yoshiji Inoue

Masashige Tada

Tsutomu Kamifuji

Masayoshi Shimamoto

Yukihiro Araya

Hiroshi Abe

Kenji Nakao

Kenji Goto

Hiroshi Ide

Hiroshi Murakami

Satoshi Fujita

Manabu Tsukamoto

Yukio Kodama

Hideki Miyake

Kazuyuki Ohmi

Yasuhiro Okazaki

Robert Ross

Shoji Tsuchioka

Teruya Nakashima

Yutaka Hayashi

Shingo Tajima

Motokuni Saeki

Yasunori Sakaguchi

Katuyuki Kurokawa

Masayasu Tanaka

Taiji Kabayama

The present invention is made to not only reduce voltage drop when a power supply circuit makes a selection between a power supply voltage from a main power supply and a backup power supply voltage from an auxiliary power supply, but also reduce the power consumption of the auxiliary power supply. The power supply circuit, which is in a semiconductor integrated circuit, includes a measurement circuit, a switch control circuit, and a switch circuit. The switch circuit includes a first switch element and a second switch element. The first switch element is coupled between an output terminal and a first input terminal. The second switch element is coupled between the output terminal and a second input terminal. The measurement circuit operates on the main power supply voltage at the first input terminal and compares the main power supply voltage with the auxiliary power supply voltage.

Semiconductor integrated circuit and operating method thereof

The disclosed invention provides a device for driving a piezoelectric element, making it possible to make an output voltage follow a control voltage during a discharging action. A charging circuit charges a piezo element through a first node. A discharging circuit discharges electric charge charged in the piezo element through the first node. A control circuit makes switching to cause the discharging circuit to perform a discharging action or cause the charging circuit to perform a charging action, based on a comparison between the magnitude of a voltage being applied to the piezo element and the magnitude of a control voltage.

Device for driving a piezoelectric element

A driving circuit supplies a suppression current (I) which reduces a decrease in a driving current (Idrive) immediately after occurrence of an overshoot at the time of the rise of the driving current (Idrive) to a laser diode (). The driving circuit draws a suppression current (I) which reduces an increase in the driving current (Idrive) immediately after occurrence of an undershoot at the time of the fall of the driving current (Idrive) from the driving current (Idrive).

Driving circuit for and semiconductor device for driving laser diode

In order to cancel an offset caused by a variation of a signal inputted from an optical pickup, variations of elements in an integrated circuit, etc., a calibration circuit which generates and feeds back an offset adjustment amount that makes the offset zero by a comparison with a reference value, and an offset adjustment circuit that makes the offset zero using the fed-back control signal are provided in an analog front-end LSI. The offset adjustment by the calibration circuit is automatically done in response to commands supplied from a digital signal processing LSI, a host control device, etc. On the other hand, as for a signal on which arithmetic processing such as gain control, addition and subtraction, is performed, the offset adjustment is performed by sending the offset adjustment amount obtained by an arithmetic operation performed by software processing of the digital signal processing LSI to the analog front-end.

Optical disk apparatus, signal processing semiconductor integrated circuit constituting the same, and operation method

There is provided a semiconductor device capable of supplying an analog input signal higher than or equal to an operating power supply voltage. An electrostatic discharge protection circuit corresponding to the analog input signal is provided for an external terminal that is supplied with an analog input signal generated with a first power supply voltage. A voltage divider resistor divides the analog input signal passing through the electrostatic discharge protection circuit into a voltage corresponding to a second power supply voltage lower that the first power supply voltage. An input circuit operating on the second power supply voltage receives the analog input signal divided by the voltage divider resistor to form an internal analog signal. There are provided first and second unidirectional elements. The first unidirectional element passes current from the input circuit's input terminal to the second power supply voltage. The second unidirectional element passes current from a circuit ground potential to a first circuit's input terminal.

Semiconductor device

Magneto-resistive (MR) head pre-amplifiers for single polarity power supply applications are presented. An exemplary pre-amplifier includes a bias network coupled to first and second input terminals of the pre-amplifier, the input terminals for receiving signals corresponding to variations in magnetic fields from an MR head. At least one gain stage having first and second input terminals and first and second output terminals for amplifying the received signals is included. A pair of coupling capacitors, each capacitor being connected between a respective input terminal of the pre-amplifier and a corresponding respective input terminal of the at least one gain stage, are further included in the pre-amplifier design. Finally, the exemplary pre-amplifier includes a pair of feedback capacitors, each capacitor being connected between respective input and output terminals of the at least one gain stage. The pre-amplifier is powered by a single polarity power supply.

Differential magneto-resistive head pre-amplifiers for single polarity power supply applications

An N-transistor switches a current of a first constant current source by a positive input pulse to generate an output pulse current where an overshoot and an undershoot appear. A P-transistor switches a current of a second constant current source by a negative correction pulse applied at timing of occurrence of the overshoot to generate a correction pulse current. Another N-transistor switches a current of a third constant current source by a positive correction pulse applied at timing of occurrence of the undershoot to generate a correction pulse current. These correction pulse currents are added to the output pulse current to obtain a current as a wavelength where the overshoot and undershoot are largely reduced.

Pulse current generation circuit

A device for measuring temperature of a semiconductor integrated circuit includes first and second current mirror circuits, an N channel transistor connected to an output terminal of the second cur rent mirror circuit, an npn transistor connected to an output terminal of the first current mirror circuit and the N channel transistor, and an operational transistor connected to a node between the second current circuit and the N channel transistor. Currents that flow from the second current mirror circuit to the N channel transistor and from the N channel transistor to the npn transistor have different temperature coefficients. The operational amplifier corrects the difference in the temperature coefficients of these currents to output a voltage of ground electric potential standard.

Device for measuring temperature of semiconductor integrated circuit

In a magnetic recording writing circuit, a current having a higher level than a write current is supplied for a period of time during rise and fall of the write current, and a current having a lower level than the write current is supplied for a period of time during overshoot at the rise and fall of the write current. Accordingly, the write current can recover quickly from overshoot.

Magnetic recording writing circuit

An H-type bridge circuit includes four transistors, two resistors, and a write head. A write current supplied from a current supply circuit including a first of the transistors and resistors flows through the write head and is received in a current receiving circuit including a second of the resistors and a fourth of the transistors, and another write current supplied from a current supply circuit including the second of the transistors and the second resistor flows through the write head and is received in a current receiving circuit including the first of the resistors and the third of the transistors. Impedance of the write head matches an output impedance of the current supply circuit and matches an input impedance of the current receiving circuit.

Current driver circuit for supplying write current to a write head while changing a flow direction of the write current

In an optical information reproduction method and apparatus with a tracking servo system using a tracking error signal in the phase difference method, the effect of the offset which varies depending on the pit depth and the lens position can be corrected and a tracking error detecting means free from the offset can be obtained. To this end, the phase comparison means are made to receive a certain set of input signals during the offset correction, and a different set of input signals during the tracking error signal detection. The offset in the tracking error signal which varies depending on the pit depth and the lens position is obtained as a voltage value, and through repeated learning control, this offset is corrected.

Method of and apparatus for optical information reproduction

In an optical information reproduction device for reproducing information from an optical disk medium on which an identification information area including first identification information shifted radially outward with respect to the center of a recording track by a specified distance and second identification information shifted radially inward with respect to the center of a recording track by a specified distance, and a user information area disposed along the center of a recording track are disposed, information is reproduced using a sum signal and a difference signal of the outputs from a split photodetector having at least two light-receiving parts disposed on opposite sides of a track tangential line. The first or second identification information signal is inverted and the direct-current component in the identification information signal and the user information signal are removed.

Growing community of inventors

Tokyo, Japan

Takehiko Umeyama