Fujitsu Corporation

Fujitsu Semiconductor Limited

Fujitsu Microelectronics Limited

Kenji Ito

Hisao Suzuki

Yoshiaki Shimizu

Masashi Kijima

A D/A conversion circuit for performing D/A conversion at high speeds. The D/A conversion circuit includes a resistor string including a plurality of resistor elements connected between a low-potential power supply and a high-potential power supply. A plurality of first switch groups are connected to the connection nodes between the resistor elements for selectively outputting voltages at the connection nodes. The outputs of the switches of the first switch groups are connected in common to a corresponding one of the nodes. The plurality of nodes are connected to an output terminal of the D/A conversion circuit via a second switch group. Predetermined switches of the first switch groups are connected in parallel to third switches to apply voltages to the nodes.

A/D conversion circuit for use with low-potential and high-potential power supplies

An A/D conversion circuit including a plurality of resistor elements connected in series between a low-potential power supply and a high-potential power supply. The A/D conversion circuit includes a plurality of comparators that compare a reference voltage divided by each of the resistor elements with an analog input voltage, the comparators having a sample-and-hold function for holding a sampled analog input voltage. The plurality of comparators also include a high-order bit comparator and a low-order bit comparator having different sampling sources. The high-order bit comparator may be configured to compare the analog input voltage and one of the reference voltages to obtain a determination result. The low-order bit comparator may old the analog voltage from the time that the low-order bit comparator retrieves the analog input voltage until the low-order bit comparator performs comparison.

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Kasugai, Japan

Kenji Ito