Patent ID: 6621340
Filing Date: 2003-09-16
Classification: H03F

Abstract:
A circuit for reducing adjacent-channel interference by pre-linearizing and pre-distorting an input signal to be transmitted via a power amplifier having a non-linear transmission characteristic and a limited dynamic range, comprising:a pre-linearization signal generator for producing a pre-linearization signal reflecting a signal portion of said input signal exceeding the dynamic range of said power amplifier; an element for expanding said pre-linearization signal along the time axis to produce an expanded pre-linearization signal reflecting an expanded version of said signal portion of said input signal exceeding said limitation; a combiner for combining said expanded pre-linearization signal and said input signal, such that said expanded version of said signal portion of said input signal exceeding said limitation is subtracted from said input signal, to produce a pre-linearized signal; a pre-distorting unit for pre-distorting said pre-linearized signal using complex pre-distortion coefficients which depend on the power of said input signal or the power of said pre-linearized signal and the non-linear transmission characteristic of said power amplifier determined in advance, such that the distortion introduced by the non-linear transmission characteristic of said power amplifier is substantially compensated for according to magnitude and phase.