the aim of the invention is to suppress interference caused by a mismatch of the power amplifier of a polar - loop transmitter . to achieve this , the crest factor of the output signal from the power amplifier is measured during operation to detect the state of the mismatch and to identify the modification of the transfer characteristic curve of the power amplifier . the crest factor that have been determined are compared with a target value and if the crest factor deviates from the target value , the bandwidth or the amplification of the amplitude closed loop is adapted accordingly ., the transmitter can thus regulate the non - linear distortion that occur as a result of the mismatch . said measures improve the linear behavior or degree of efficiency of the power amplifier .