| 摘要 |
PURPOSE: An operational amplifier and a digital-analog converter using the same are provided to reduce an influence of offset voltage by adding an offset removal circuit and a current sink control circuit to a driving circuit. CONSTITUTION: An operational amplifier includes a differential amplifier, a current sink circuit, an offset removal circuit, a first current sink control circuit, and a second current sink control circuit. The differential amplifier is used for amplifying a difference between an input signal of a first input terminal connected a control terminal of a first transistor(T23) and an input signal a second input terminal connected to a control terminal of a second transistor(T24). The current sink circuit includes a third transistor(T25) and a fourth transistor(T26) in order to supply the current to the differential amplifier. The offset removal circuit is used for storing an offset voltage of the differential amplifier during a reset period and supplying the voltage having the opposite polarity to the offset voltage to the control terminal of the second transistor(T24). The first current sink control circuit is used for storing the offset voltage during the reset period and controlling the third transistor(T25). The second current sink control circuit is used for storing the offset voltage during the reset period and controlling the fourth transistor(T26).
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