The invention relates to an apparatus for generating an error signal from an input signal, the error signal to be used for generating a transmit signal, the apparatus comprising: means (103) for distorting the input signal to obtain a distorted signal, means (105) for calculating a preliminary error signal representing a difference between the input signal and the distorted signal or representing the input signal, means (107) for manipulating the preliminary error signal to obtain the error signal, wherein the means (107) for manipulating is configured for varying a preliminary error signal value to obtain an error signal value which is non-equal to zero.