Baseband predistortion system for the adaptive linearization of power amplifiers
First Claim
1. A baseband predistortion system for providing adaptive linearization of a power amplifier, having an adaptive predistortion circuit with at least one updatable error table for providing updatable error table signals used for predistorting an input signal, and address generating means for generating addresses of said at least one updatable error table,characterized in that said address generating means generates decoded address signals for said at least one updatable error table as a function of the value of the amplitude of said input signal.
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Abstract
The invention relates to a baseband predistortion system for the adaptive linearization of power amplifiers and to a radiotransmitter using the predistortion system. It is based upon the updating of two error tables, one for the amplitude and one for the phase, whose content is used for correcting the baseband samples. The content of the tables is obtained by accumulating the difference, suitably weighed, between the sampling entering the predistortion device and the demodulated feedback value.
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Citations
11 Claims
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1. A baseband predistortion system for providing adaptive linearization of a power amplifier, having an adaptive predistortion circuit with at least one updatable error table for providing updatable error table signals used for predistorting an input signal, and address generating means for generating addresses of said at least one updatable error table,
characterized in that said address generating means generates decoded address signals for said at least one updatable error table as a function of the value of the amplitude of said input signal.
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9. A baseband predistortion system for providing adaptive linearization of a power amplifier, having a predistortion circuit with at least one updatable error table for providing updatable error table signals used for predistorting an input signal, and address generating means for generating addresses of said at least one updatable error table,
characterized in that said address generating means generates the addresses in such a way that every address on average has the same probability of occurrence.
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11. A radio transmitter for transmitting a signal on an antenna, the radio transmitter having an encoder (COD) for encoding an input signal, an adaptive predistortion device (PREDIST), means for converting an output signal of the adaptive predistortion device (PREDIST) by digital to analog converters (D/A), means for modulating (MOD) output signals of the digital to analog converters, means for amplifying (PA) the output signals of the modulating means (MOD), a demodulator (DEM) connected to an output signal of the amplifying means (PA), analog to digital converters (A/D) connected to the output of the demodulator (DEM), the output of the analog to digital converters (A/D) connected to the adaptive predistortion device (PREDIST), a local oscillator (LO) for generating oscillating signals for the modulating means (MOD) and the demodulator (DEM), and means for connecting the output signal of the amplifying means (PA) to the antenna, characterized in that
the adaptive predistortion device (PREDIST) provide adaptive linearization of the amplifying means (PA), and wherein the adaptive predistortion device (PREDIST) includes at least one updatable error table (err-ρ - , err-θ
), and address generating means for generating decoded address signals for said at least one updatable error table (err-ρ
, err-θ
) that provides updatable error table signals used for predistorting said input signal, and wherein the address generating means generates the decoded address signals as a function of the value of the amplitude of said input signal.
- , err-θ
Specification