| 摘要 |
PROBLEM TO BE SOLVED: To provide a current/voltage control circuit of low cost and high reliability which does not require an individual trimming circuit and can automatically adjust with the effect of input offset voltage eliminated. SOLUTION: With a switch circuit 7 short-circuited, an input setting value of an up/down counter circuit is set to be zero, a digital value of a count circuit 1 is set to a minimum value. In addition, the digital value is counted up until an output value [c] of a second operational amplifier circuit 3 reaches an output value [d] of a first operational amplifier circuit 4, the digital value, when it reaches the output value [d], is held in the count circuit 1, and an adjustment is made for eliminating the effect of input offset voltages of first and second operational amplifiers 3, 4. By making the adjustment regularly and automatically, reduction of manufacturing cost and high reliability can be attained. COPYRIGHT: (C)2004,JPO
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