Patent ID: 6314142
Filing Date: 2001-11-06
Classification: H03F

Abstract:
A circuit for predistorting an analog signal to be transmitted via a non-linear channel, comprising:an envelope detector for detecting an envelope of the analog signal;a quantizer for forming quantized envelope values on the basis of the detected envelope;a table for storing complex predistortion coefficients,each complex predistortion coefficient having an in-phase component and a quadrature component,the complex predistortion coefficients are stored in the table depending on sectionwise linearization sections of a previously detected relation between an output signal from the non-linear channel and an input signal into the non-linear channel,each linearization section having associated there with a complex predistortion coefficient,each complex predistortion coefficient stored in said table being addressable by a quantinzed envelope value, each quantinzed envelope value lying in one of the linearization sections,the complex predistortion coefficients being determined such that the distortion introduced by the non-linear channel is substantially compensated for according to magnitude and phase; anda predistorter separated from said non-linear channel and used for complex predistortion of the signal with the complex predistortion coefficients,the predistorter having an I-channel for receiving the in-phase component of the complex predistortion component addressed by an envelope value of the analog signal, and a Q-channel for receiving the quadrature component of the complex predistortion component,the predistorter being arranged for IQ-weighting the analog signal using the predistortion coefficient received via the I- and Q-channel.