Yamaha Corporation

Shoji Yasui

Masayoshi Omura

Makoto Kaneko

Masao Noro

Kunito Takahashi

Hideyuki Yamada

There is provided a correction circuit for a D/A converter, comprising: a constant current source to be connected between high- and low-potential power source lines for supplying a power source voltage to the D/A converter; and a current controller which is adapted to control a current flowing to the constant current source in accordance with an input digital signal to the D/A converter, so as to reduce a variation of a sum of currents which, when the input digital signal to the D/A converter is changed, flows to the low-potential power source line from the high-potential power source line through the D/A converter and the constant current source, respectively.

Correction circuit for D/A converter

With regard to a temperature sensor, a control logic circuit conducts control of the temperature sensor. During preparation of the temperature sensor, the control logic circuit reads the result of measurement of the property pertaining to the ambient temperature from the temperature sensor circuit, obtains the initial value and correction value from the result, and stores the pertinent values in the fuse memory. At times of operation of the temperature sensor, the control logic circuit reads the initial value and correction value from the fuse memory, and corrects the measurement values of the temperature sensor circuit using the pertinent values.

Geomagnetic sensor and geomagnetic sensor correction method, temperature sensor and temperature sensor correction method, geomagnetism detection device

A geomagnetic sensor including a geomagnetism detection unit; a fuse memory for storing prescribed data according to a state of the electrical cut-off or connection; a correction data writing unit for inputting measurement values of said geomagnetism detection unit during manufacture, for obtaining correction values that correct a temperature property of the measurement values of the geomagnetism detection unit, and for writing said correction values into said fuse memory; a correction data reading unit for reading said correction values from said fuse memory at times of actual use after manufacture; and a correction unit for inputting the measurement values of said geomagnetism detection unit at times of actual use, and for correcting the measurement values of said geomagnetism detection unit based on the correction values read by said correction data reading unit.

The present invention provides a high-accuracy and multi-bit D/A converter which can be produced using a CMOS process. A resistor string is formed of a plurality of resistors connected in series. A switch matrix has switch strings each formed of switches each having one end thereof connected to a corresponding one of junctions of the resistors and having respective other ends commonly connected to one of common junctions. A decoder turns on and off the switches of the switch strings according to more significant bits of data for conversion. A less significant bits-conversion circuit generates a voltage corresponding to less significant bits of the data for conversion and outputs the voltage. An operational amplifier carries out addition or subtraction of a voltage at each of the common junctions and an output from the less significant bits-conversion circuit.

Digital-to-analog converter

A reference voltage generating circuit is provided with a reference voltage output terminal, a voltage dividing circuit that divides a voltage supplied from a power source, and an integrating circuit having a given time constant, for integrating a voltage of the divided voltage output terminal of the voltage dividing circuit and generating a reference voltage as a result of integration to the reference voltage output terminal. A high-speed charging circuit is connected to the reference voltage output terminal, for charging the integrating circuit at a high speed when the power source is turned on, to elevate a voltage of the reference voltage output terminal at a speed higher than a speed determined by the time constant of the integrating circuit. A comparator circuit compares the voltage of the divided voltage output terminal with the voltage of the reference voltage output terminal, and turns off the high-speed charging circuit when a difference between the voltage of the divided voltage output terminal and the voltage of the reference voltage output terminal becomes equal to or smaller than a predetermined level.

Growing community of inventors

Hamamatsu, Japan

Shoji Yasui