| 摘要 |
PROBLEM TO BE SOLVED: To provide a distortion compensation amplifying circuit that prevents wrong distortion compensation from being optimized and adjusted, when the level of an input signal is reduced. SOLUTION: A distributor 1 allows the input signal to branch into two paths. A vector adjustment circuit 2 allows one signal to be subjected to vector adjustment. A main amplifier 3 amplifies the result. A delay line 5 allows the other to be subjected to phase adjustment. A delay line 9 is subjected to the phase adjustment, after a pilot signal is injected by the output of the main amplifier 3. A vector adjustment circuit 10 is subjected to phase adjustment after the output of the delay line 5, and the signal that is allowed to branch from the output of the main amplifier 3 are multiplexed. An auxiliary amplifier 11 amplifies the resultant signal. A control part 13 detects the level of the input signal, the output of the auxiliary amplifier 11, and a multiplexed output signal, and fixes the amount of attenuation and phase shift in the vector adjustment circuit 2 of at least a distortion extraction loop by control data; while the level of the input signal is high, when the level of the input signal becomes lower than a preset level.
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