| 摘要 |
PROBLEM TO BE SOLVED: To provide a multi-band amplifier circuit or the like which can use one amplifier in a multi-band and obtains sufficient gain and high stability over a frequency band of a wide range. SOLUTION: In the multi-band amplifier circuit 30 configured by connecting a resistance R2 for bias for determining a bias point of a transistor between an input line LN and a ground line LG of an amplifier 31 configured by including the transistor, a low-resistance Rb having a resistance value lower than the resistance for bias is inserted between the input line and the resistance for bias to be connected, and a bypass capacitor Cb for bypassing high frequency components of the input line for attenuation is provided to constitute a serial body with the whole low-resistance Rb or a portion of it so as to be connected to the ground line and also selectively connected to the whole low-resistance Rb or the portion of it. COPYRIGHT: (C)2009,JPO&INPIT
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