Kawasaki Microelectronics, Inc.

Masatoshi Takada

Masayuki Ueno

Hiroshi Ogasawara

Tatsuyuki Araki

Chie Serizawa

A high accuracy D/A converter includes D/A converter sections including 64 current cells for outputting a current corresponding to 1 LSB of 8-bit input data and a D/A converter section including 63 current cells, a reference current generating section for supplying the respective D/A converter sections with reference currents, and a decoder for activating each of the current cells from the D/A converter sections to the D/A converter section in the stated order in a cyclic manner when the 8-bit input data value is increased, and deactivating one each of the activated current cells from the D/A converter section to the D/A converter section in the stated order in a cyclic manner when the 8-bit input data value is decreased.

D/A converter

An error correction circuit and a folding ADC are provided. In the folding ADC, the range of the input voltage to an upper ADC circuit and to a lower ADC circuit is shifted by a predetermined voltage toward higher and lower electric potential sides. The error correction circuit outputs the conversion result of the upper bits as is, or corrects the conversion result of the upper bits by either subtracting or adding 1 from or to the conversion result of the upper bits in accordance with the least significant bit within the conversion result of the upper bits and in accordance with the polarity of a code having different polarities between a period in which the voltage level of one folding signal among a plurality of folding signals output from the folding circuit is higher than the center level and a period in which the voltage level is lower.

Error correction circuit and A/D converter

In an I/V converter circuit and a D/A converter, a wide pass band for signal can be obtained and current consumption can be reduced. A current is supplied through an input terminal to a first node, and a first bias current is supplied from a first bias-current generating circuit to the first node. The current supplied to the first node is mirrored to a second node, and a second bias current is supplied from a second bias-current generating circuit to the second node. A first control circuit controls first and second elements of a current mirror circuit so that the voltage of the first node is substantially equal to a bias voltage, a third element converts a current flowing therethrough to a voltage by using the bias voltage as reference, and a second control circuit controls the voltage output from an output terminal so that the voltage of the second node is substantially equal to the bias voltage.

I/V converter circuit and D/A converter

A current/voltage converter includes a current source connected to a first node; a first transistor element connected between the first node and a power supply or ground; a second transistor element which is connected between a second node and the power supply or ground, whose control terminal is connected to that of the first transistor element; a first control circuit which controls the voltages of control terminals of the first and second transistor elements so that the voltage of the first node becomes substantially equal to that of a bias voltage as one of inputs to the first control circuit; a second control circuit controlling the voltage of the second node so as to become substantially equal to that of the first node; and a resistance element one end of which is connected to the second node, and which converts the current flowing through the second transistor element into a voltage.

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Chiba, Japan

Masatoshi Takada