| 摘要 |
PROBLEM TO BE SOLVED: To reduce power consumption by an idle current in an amplifying circuit provided with a push-pull circuit of class AB operation at an output stage. SOLUTION: An amplifier 26 controls one transistor Tr1 constituting the push-pull circuit of an output stage circuit 24 to operate in the class AB mode corresponding to the positive period of an differential input V<SB>IN</SB>. A transistor Tr3 turns ON corresponding to the positive period of V<SB>IN</SB>based on an output of the amplifier 26 and sets the other transistor Tr2 to the cut-off state by grounding the gate of the transistor Tr2 constituting the push-pull circuit. Similarly, an amplifier 28 controls the transistor Tr2 to operate in the class AB mode corresponding to the negative period of the differential input V<SB>IN</SB>and sets the transistor Tr1 to the cut-off state by turning on a transistor Tr4 to ground the gate of the transistor Tr1. COPYRIGHT: (C)2009,JPO&INPIT
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