| 摘要 |
PURPOSE:To reduce a variation of a bipolar offset voltage by constituting a current mirror circuit by using a reference current of a D/A converting circuit, and allowing an output current of this circuit to flow as a bipolar current to an input terminal of a comparator. CONSTITUTION:A current mirror circuit is constituted of a transistor 3 and 4, and a reference current I0 of a D/A converting circuit 10 is supplied from a reference current source 5. Also, an output terminal 16 of the current mirror circuit is connected to a negative side input terminal of a comparator circuit 11. Resistance values of a resistance 1 and a resistance 2 are set to a ratio of 2:1, and from the output terminal 16 of the current mirror circuit, a current of 2I0 becomes a bipolar current and flows out. This bipolar current interlocks and moves against a variation of the reference current I0 of the A/A converting circuit 10, therefore, a variation of a bipolar offset voltage based on a variation of the reference current I0 can be eliminated.
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