| 摘要 |
PROBLEM TO BE SOLVED: To fix the base potential of a transistor while inhibiting the increase of a layout area. SOLUTION: A Zener diode D1 is connected between a power-supply line 2 and a base so as to be directed in the opposite direction. Since a leakage current flowing through the Zener diode D1 is made sufficiently smaller than the current Ia of a constant-current circuit 3 under the state in which a switch 5 is turned on, the error of a mirror ratio is reduced. When the potential of the base line of the transistors Q1 to Q4 lowers under the state in which the switch 5 is turned off, the Zener diode D1 works so as to suppress the lowering of the base potential because the leakage current of the Zener diode D1 increases. The element size of the Zener diode D1 is made remarkably smaller than a resistance element having a high resistance value in the same extent as a resistance value in the opposite direction. COPYRIGHT: (C)2007,JPO&INPIT
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