| 摘要 |
PROBLEM TO BE SOLVED: To extend the output voltage range of an operational amplifier without boosting and applying a power supply voltage to the output transistor. SOLUTION: Output transistors Tr31 and Tr32 provided between a power source and a ground line are composed of NPN transistors, and a differential amplifier circuit 10 on the input stage is constituted to output signals respectively corresponding to the potentials of respective input terminals Tn and Tp. Then, a control circuit 40 on the middle stage is constituted to drive the output transistors Tr31 and Tr32 respectively corresponding to respective signals outputted from the differential amplifier circuit 10. As a result, in comparison with a conventional operational amplifier having the output stage in push-pull configuration, a bottom output voltage can be lowered for Vf. In this case, when the output transistor Tr 31 on the side of positive pole is composed of a PNP transistor, a peak output voltage can be improved for Vf and the output voltage range can be more extended.
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