Patent ID: 6798843
Filing Date: 2004-09-28
Classification: H03F

Abstract:
A system for digitally predistorting a wideband input signal to a power amplifier, comprising:a multi-dimensional data structure in which each element stores a set of compensation parameters, including filter coefficients, for predistorting the wideband input signal to compensate for nonlinearities in an amplification process; an addressing circuit that generates indexes for each of the multiple dimensions of the data structure, based at least upon characteristics of the input signal, to read sets of compensation parameters from the data structure, wherein the addressing circuit generates a first index that represents an instantaneous characteristic of the wideband input signal, and generates a second index that represents an averaged characteristic of the wideband input signal, and uses the first and second indexes in combination to address the multi-dimensional data structure such that the first and second indexes correspond respectively to first and second dimensions of the multi-dimensional data structure; and a digital compensation circuit that predistorts the input signal in real time using the compensation parameters read from the multi-dimensional data structure according to the addressing circuit, wherein the digital compensation circuit comprises a finite impulse response (FIR) filter for which coefficient sets are read from the multi-dimensional data structure; whereby a predistortion function applied by the digital compensation circuit is dependent upon the characteristics of the wideband input signal.