| 摘要 |
The present invention has for its object to provide, in an environment where plural radio systems coexist, a feed forward amplifier for multiple frequency bands, capable of adaptively selecting the frequency band which is used. The feed forward amplifier of the present invention comprises a distortion detection circuit and a distortion elimination circuit and has first and second variable frequency band extractors 25 a and 25 b provided in series with respective vector adjustment paths 21 a and 21 b. Also, the feed forward amplifier comprises a frequency band controller which varies the frequency band of variable frequency band extractors 25 a and 25 b and has been designed, by changing the frequency band of first and second variable frequency band extractors 25 a and 25 b in response to a frequency switching request from the outside, to be able to adaptively control the frequency band in which distortion is compensated.
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