| 摘要 |
PROBLEM TO BE SOLVED: To provide an operational amplifier which has a simple circuit constitution and is less affected by an offset voltage. SOLUTION: A differential amplifying circuit includes a differential pair and a cascade current mirror circuit forming a load circuit for the differential pair. The cascade current mirror circuit has a first transistor pair having control terminals connected in common, and second and third transistor pairs receiving a bias signal at the common-connected control terminals respectively. The second transistor pair is straight-connected between the first transistor pair, and an input terminal and an output terminal of the cascade current mirror circuit, and the third transistor pair are cross-connected between the first transistor pair, and the input terminal and output terminal of the cascade current mirror circuit. The second transistor pair and third transistor pair have their active states and inactive states controlled by switching bias voltage values respectively such that when one transistor pair are active, the other pair are inactive. COPYRIGHT: (C)2007,JPO&INPIT
|
