Fujitsu Corporation

Fujitsu Semiconductor Limited

Fujitsu Microelectronics Limited

Shogo Itoh

Hisao Suzuki

An operational amplifier includes a first amplifier to which an input signal is applied, and a second amplifier to which an output of the first amplifier is applied, wherein the second amplifier includes a first transistor including a gate to which the output of the first amplifier is applied, and a second transistor including a gate to which the output of the first amplifier is applied, and a drain coupled to a source of the first transistor.

Operational amplifier

A digital-analog converter including a first selection circuit of switch elements, which are coupled to each other and to a high potential power supply, and a second selection circuit of switch elements, which are coupled to each other and to a low potential power supply. First and second voltage dividing circuit each include series-connected resistor elements, each coupled between adjacent switch elements of the corresponding selection circuit. A control circuit provides a control signal to the selection circuits to activate one of the switch elements in each selection circuit and couple the activated switch element to the corresponding potential power supply. The first and second voltage dividing circuits divide voltages of the high and low potential power supplies with the resistor elements between the activated switch elements.

D/A converter

It is intended to provide an A/D converter circuit with which, by using a clock signal, on the basis of an analog voltage inputted a predetermined time past, it is possible to select suitably comparators to be operated and comparators to be rested, and which has small consumed power. A parallel-type A/D-converter circuitconverts an analog voltage VIN to a digital value DOUT at intervals of a predetermined period by means of a clock signal CLK using chopper-type comparators. The comparatorscan each be set by first and second setting signals CONTA etc. to either of an operating state and a resting state. A comparator control circuit sectionperforms logical processing on the comparator outputs OUT&#x2013;OUTin the preceding conversion to generate the first and second setting signals CONTA etc., and brings some of the comparators to the operating state and holds the remaining comparators in the resting state.

Current supply circuit

It is intended to provide an A/D converter circuit with which, by using a clock signal, on the basis of an analog voltage inputted a predetermined time past, it is possible to select suitably comparators to be operated and comparators to be rested, and which has small consumed power. A parallel-type A/D-converter circuit converts an analog voltage VIN to a digital value DOUT at intervals of a predetermined period by means of a clock signal CLK using chopper-type comparators . The comparators can each be set by first and second setting signals CONT A etc. to either of an operating state and a resting state. A comparator control circuit section performs logical processing on the comparator outputs OUT -OUT in the preceding conversion to generate the first and second setting signals CONT A etc., and brings some of the comparators to the operating state and holds the remaining comparators in the resting state.

Growing community of inventors

Kasugai, Japan

Shogo Itoh