| 摘要 |
PROBLEM TO BE SOLVED: To provide an amplifier circuit which maintains an input impedance constant, while being able to change a gain. SOLUTION: This amplifier circuit has: a source grounding type amplifier (101); an output load (102) connected to an output terminal of the source grounding type amplifier; a buffer circuit (103) connected to the output terminal of the source grounding type amplifier; a feedback circuit (104) connected to between an output terminal of the buffer circuit and an input terminal of the source grounding type amplifier; and a control circuit (105) for controlling an impedance of the feedback circuit in response to a gain of the source grounding type amplifier. COPYRIGHT: (C)2009,JPO&INPIT
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