| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-frequency amplifier circuit that can prevent deterioration in speech quality during low gain and suppress radiation of unwanted radio waves during low gain. SOLUTION: An amplifier 3, a filter 4, and changeover switches 2, 5 causing the amplifier 3 and a filter 4 to function selectively are provided between a signal input terminal 1 and a signal output terminal 6. A high-frequency signal given to the signal input terminal 1 is amplified by the amplifier 3, and the amplified signal is given to the signal output terminal 6 in a 1st mode with a high gain. Furthermore, the high-frequency signal given to the signal input terminal 1 is given to a filter 4, desired frequency components in the high-frequency signal is fed to the signal output terminal 6 to attenuate unwanted frequency components in a 2nd mode with a low gain.
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