| 摘要 |
PROBLEM TO BE SOLVED: To provide an operational amplifier for widening the range of output voltage stably with low power consumption without increasing the circuit scale, and to provide a drive circuit and an electrooptical device. SOLUTION: The operational amplifier 100 comprises a differential amplifier 110 having a differential transistor pair which is supplied with an input voltage and an output voltage to the gate and a current source transistor creating the sum of drain currents of the differential transistor pair and amplifying the difference between the input voltage and the output voltage, and a drive transistor having a gate controlled based on the voltage at the output node of the differential amplifier to create an output voltage. Potential of an impurity layer for forming the channel region of the current source transistor is set independently from the potential of the impurity layer for forming the channel region of other transistor. Current drive capability of the operational amplifier 100 is controlled by fixing the gate voltage of the current source transistor and altering at least one of the potential of the impurity layer and the potential of the source region. COPYRIGHT: (C)2007,JPO&INPIT
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