| 摘要 |
A transmitter comprises a device ( 20 ) for frequency up-conversion of a communication signal having at least two consecutive frequency conversion stages, a power amplifier ( 27 ) for amplifying the output signal therefrom for obtaining a transmission signal and means ( 29 ) for extracting the transmission signal. It also has a device for frequency down-conversion of said extracted transmission signal to the same frequency as the communication signal before said up-conversion for creating a feedback signal. Said two devices use the same local oscillators ( 25, 26 ). The transmitter also has means for signal parameter adaptation of the communication signal on basis of the feedback signal for obtaining a desired character of the transmission signal. The frequency down-conversion device comprises a local oscillator combiner ( 30 ) producing a combined frequency signal used for frequency down-conversion of the transmission signal reducing the number of conversion stages in the path of the extracted transmission signal with respect to the corresponding number of the frequency up-conversion device.
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