| 摘要 |
PURPOSE:To adjust stable an offset voltage by using a common mode rejection ratio of a differential amplifier constituted in an IC so as to reduce the temperature dependency of offset adjustment. CONSTITUTION:The differential amplifier 11 is formed on an IC board 1', a collector of a transistor (TR) Q1 is connected to an offset adjusting terminal of an IC circuit 2, bases of TRs Q1, Q2 are connected respectively to a resistance voltage dividing point placed at the outside of the board and an offset is cancelled at an output terminal by flowing a collector current of the TRQ1 while changing the ratio of resistors 15 and 16. Since the resistors change with the same tendency as the ambient temperature change, the base potential of the TRs Q1, Q2 is unchanged and even if the resistor of the IC circuit 2 is fluctuated because of temperature change, it is compensated by the common mode rejection ratio of the differential amplifier 11, allowing to adjust the offset as an initial value.
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