| 摘要 |
PROBLEM TO BE SOLVED: To achieve a low noise amplifier circuit with excellent noise characteristics with simple configuration at low cost by suppressing small the deterioration in a noise index while removing an unwanted frequency component. SOLUTION: In a low noise amplifier circuit of the present invention, a filter 12 for removing an unwanted frequency component by passing a signal component of a desired frequency band in an input signal is provided on the pre-stage of an amplification element included in an LNA 13, and an input matching circuit is provided to be connected between an output side of the filter 12 and an input side of the amplification element. When a reflection coefficient watching an output side of a circuit portion, where the input matching circuit is connected to the filter 12, from the input side of the amplification element is defined asΓs, the filter 12 is adjusted so that part of or all impedance, in adjusting theΓs into desired reflection coefficient, may become output impedance different from characteristic impedance. COPYRIGHT: (C)2007,JPO&INPIT
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