| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a D/A converter which controls the gradient of a reference signal for single slope integration type A/D conversion precisely. <P>SOLUTION: Gain control is made to a first D/A converter 302 for obtaining the reference signal, based on a D/A output current Igain obtained by a second D/A converter 304. For respective current source cells 353, 355 in a current source cell 350, the operating current is defined by a bias current Vbais corresponding to the D/A output current Igain. At the first D/A converter 302, a low-order bit control unit 330 performs dividing operation, and uses a 1/2^k division clock for selecting a low-order current source cell 533 of a weighting current value. A high-order bit control unit 340 uses a prescribed division clock generated by the division operation of the low-order bit control unit 330 as a shift clock, sets the shift output of each shift register in a shift register section 342 to a high level successively, and uses the shift output for selecting the high-order current source cell 355 of the same weighting current successively. <P>COPYRIGHT: (C)2007,JPO&INPIT</p> |
