Transmitter and associated method for reducing the adjacent channel power during wireless communications

A method for removing at least some out of band signals from a signal output by a transmitter including at least one non-linear element, comprising:

• for each of a plurality of different input signals, predetermining an amplitude modification and a phase modification of the respective input signal which would remove at least some out of band spectral signals from the transmitted output signal;
• storing the amplitude and phase modifications for each of the plurality of different input signals;
• independently applying the amplitude modification and the phase modification to the input signal, wherein applying the amplitude modification comprises applying the amplitude modification after all non-linear elements of the transmitter.

A transmitter for improving the spectral characteristics of a transmitted output signal, comprising:

• a modulator, the modulator receiving a digital signal sample and subjecting the digital signal sample to a first filter for determining phase shift and amplitude variation information produced by the filter;
• a table for storing the phase shift and amplitude variation information, wherein phase shift and amplitude variation information is received from the table in response to a digital signal input, such that the phase shift and amplitude variation information can be independently applied to the digital signal input to produce a modulated signal, such that the filter can be eliminated.