| 摘要 |
PROBLEM TO BE SOLVED: To reduce noise in a comparison circuit and to improve AD conversion precision without lowering an apparent conversion speed in a successive approximation type AD conversion circuit. SOLUTION: The successive approximation type AD converter circuit that includes: a comparison circuit which is cascade connected via a coupling capacity, is provided with a plurality of amplification stages, and determines volume of input analog voltage and comparison voltage; a register for successively taking in determination results of the comparison circuit and holding them; and a local DA converter circuit for converting a value of the register into voltage and generating the comparison voltage includes. Here, load capacity adjustment means (16) connected to output terminals of the amplification stages of the comparison circuit (11), and a control circuit (15) for generating a signal which changes a capacity value of the load capacity adjustment means, are prepared. When converting a higher order bit, a capacity value of the load capacity adjustment means is decreased; and when converting a lower order bit, a capacity value of the load capacity adjustment means is increased. COPYRIGHT: (C)2011,JPO&INPIT
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