| 摘要 |
PURPOSE:To obtain a current source circuit wherein an input current is linearly proportional to an output current, by controlling a current flowing to a photoelectric conversion element in an optical coupling element, and connecting the optical coupling elements so that the current, which is proportional to the current flowing the element, flows into a photoelectric conversion element of an output optical coupling element. CONSTITUTION:In a current source circuit, a control system, which determines a current value, is formed by an input current source Iin, a control transistor Q1, and a first optical coupling element PC1. In this control system, a feedback loop comprising the control transistor Q1 and the first optical coupling element PC1 performs control so that a collector current IC1 of a transistor 3 of the first optical coupling element PC1 becomes equal toan input current Iin from the input current source Iin. An input current IF2 to a second optical coupling element PC2 is the same current as an input current IF1to the first optical coupling element PC1. Therefore, when the characteristics of the first and second optical coupling elements PC1 and PC2 are equal, an output current Iout agrees with the input current Iin from the input current source Iin. |
