Abstract: An exciting coil drive circuit of a magnetic sensor comprises a D/A converter that receives input of digital data for detecting a magnetic field; a first amplifier that outputs a drive signal P applied to one end of an exciting coil of the magnetic sensor based on the output signal of the D/A converter; and a second amplifier that outputs a drive signal N applied to the other end of the exciting coil based on the output signal of the D/A converter, the drive signal N being an inversion signal of the drive signal P, the drive signal N intersecting with the drive signal P twice or more.

Abstract: A conventional inverting amplifier has a problem that an oscillation may be induced depending on a structure of an internal amplifier. This invention offers an inverting amplifier having a multi-stage amplifier that is provided with a first transistor that amplifies an input signal, a second transistor that amplifies an output signal of the first transistor, a third transistor that amplifies an output signal of the second transistor and an internal feedback resistor that feeds back an output signal of the third transistor to an output node of the first transistor. With the structure described above, a required gain can be set without inducing oscillation, because a gain of the multi-stage amplifier composed of three-stage transistors can be reduced.

Abstract: With a microphone amplifier using an operational amplifier, there has been a problem that a sensitivity of the condenser microphone is reduced by an influence of a parasitic capacitance generated at an input terminal of the operational amplifier. This invention offers a microphone amplifier having a condenser microphone that converts a sound into a voltage signal, an operational amplifier having an inverting input terminal to which the voltage signal from the condenser microphone is applied and a non-inverting input terminal to which a direct current bias voltage is applied, a capacitor connected between the inverting input terminal and an output terminal of the operational amplifier, and a resistor connected between the inverting input terminal and the output terminal of the operational amplifier.

Abstract: A method of manufacturing a purified product of a liquid medium-chain alkyl-modified polydimethylsiloxane that is free of a specific (unpleasant) odor and is practically odorless, the method comprising the steps of: [A] synthesizing a liquid medium-chain alkyl-modified polydimethylsiloxane by carrying out a hydrosilylation reaction between a hydrosilyl-containing polydimethylsiloxane and an ?-olefin with 4 to 18 carbon atoms; and [B] subjecting a crude product of the liquid medium-chain alkyl-modified polydimethylsiloxane obtained in preceding step [A] to an odor-removing treatment by conducting a hydrogenation reaction which is carried out in the presence of a hydrogenation catalyst.

Abstract: An exciting coil drive circuit of a magnetic sensor comprises a D/A converter that receives input of digital data for detecting a magnetic field; a first amplifier that outputs a drive signal P applied to one end of an exciting coil of the magnetic sensor based on the output signal of the D/A converter; and a second amplifier that outputs a drive signal N applied to the other end of the exciting coil based on the output signal of the D/A converter, the drive signal N being an inversion signal of the drive signal P, the drive signal N intersecting with the drive signal P twice or more.

Abstract: A signal detection circuit of a magnetic sensor is disclosed which comprises a differential amplifier to which an output voltage of a detecting coil of the magnetic sensor is applied; a comparator to which the output of the differential amplifier is input, the comparator outputting a digital signal having one logical value while outputting each of two adjacent spike voltages included in the output voltage; and a counter that counts the number of pulses of a clock in a period when the output of the comparator has one logical value.

Abstract: In a reference current generating circuit, an output voltage of a regulator is divided by a resistance dividing circuit consisting of resistors to generate a micro reference voltage. It is possible to connect and disconnect the resistance dividing circuit using a switch consisting of a transistor. A switch consisting of a transistor is provided between a connection point of the resistors and a reference voltage output terminal. A capacitor is connected to the reference voltage output terminal. The transistors are periodically subjected to ON/OFF control according to a clock pulse outputted by a control circuit. The capacitor is charged to a reference voltage when the transistors are on and keeps the reference voltage output terminal at the reference voltage when the transistors are off. A current mirror circuit uses the micro reference voltage to generate a micro reference current while suppressing an increase in a resistance of a reference resistor that determines an output current.

Abstract: By including a circuit that, when receiving gradation data that indicates a gradation for making a luminescence element emit light, generates a driving voltage VDRV greater than or equal to a reference potential (ground potential) when a gradation indicated by the gradation data is greater than or equal to a predetermined threshold value, and that generates a driving voltage VDRV less than the reference potential (ground potential), when a gradation indicated by the gradation data is smaller than the predetermined threshold value, a driving voltage VDRV whose voltage value corresponds to a certain gradation for causing the luminescence element to emit light is created, and, by supplying the luminescence element with the driving voltage VDRV, the luminescence element is two-side driven and made to emit light. Accordingly, the lifetime of the element is extended.