Matsushita Electric Industrial Co., Ltd.

Haruhisa Takata

Seiji Watanabe

Takahiro Bokui

Kazuhiko Nishikawa

The successive comparison analog-to-digital (A-D) converter includes a plurality of capacitors, a plurality of first analog switches, a plurality of second analog switches, a plurality of third analog switches, a voltage comparator, and a state controller. Each of the plurality of capacitors has a capacitance weighted with a prescribed weighting factor. Each of the plurality of first analog switches has an on-state resistance weighted with a prescribed weighting factor. In the successive comparison A-D converter, a first analog switch corresponding to a capacitor having a capacitance weighted with a larger weighting factor has an on-state resistance weighted with a smaller weighting factor, whereby a time constant for this capacitor can be reduced. As a result, the difference in time constant between the capacitors is reduced. This enables reduction in time required to precharge (sample and hold) an analog input, improving the A-D conversion speed.

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Osaka, Japan

Haruhisa Takata