Systems and methods to compensate for memory effects using enhanced memory polynomials
View Patent ↗A system for mitigating non-linearity distortions from a memory effect is disclosed. The system includes an enhanced predistortion component, a power amplifier, and a lookup table. The enhanced predistortion component is configured to receive an input signal, to obtain a plurality of enhanced memory polynomials based on a plurality of samples of the input signal and to generate a pre-distorted signal from the input signal according to the enhanced memory polynomials and the plurality of samples of the input signal. The power amplifier is configured to receive the pre-distorted signal and to generate an output signal.
1. A method for mitigating linearity distortions and distortions from memory effect, the method comprising:
receiving an input signal;
sampling the input signal using a plurality of delay elements to obtain a plurality of samples, the plurality of samples including a current sample and one or more previous samples of the input signal;
obtaining memory polynomials according to the current sample and the one or more previous samples;
obtaining enhanced memory polynomials according to the current sample and the one or more previous samples;
generating a plurality of memory polynomial stage outputs by combining the memory polynomials with the current sample and the one or more previous samples;
combining the plurality of memory polynomial stage outputs into a first pre-distorted signal of the input signal;
generating a plurality of enhanced memory polynomial stage outputs by combining the enhanced memory polynomials with the one or more previous samples;
combining the plurality of enhanced memory polynomial stage outputs into a second pre-distorted signal of the input signal; and
generating an enhanced pre-distorted signal by combining the first pre-distorted signal and the second pre-distorted signal and generating the enhanced pre-distorted signal from only the first pre-distorted signal on an enhanced polynomial component being OFF.
2. The method of claim 1 , further comprising generating an amplifier output signal from the pre-distorted signal.
3. The method of claim 1 , further comprising generating an error according to the pre-distorted signal and the amplifier output signal.
4. The method of claim 3 , further comprising performing a training process to adjust the enhanced polynomials upon the error exceeding a selected threshold, wherein the training process includes distorting the output signal using at least the enhanced memory polynomials, comparing the pre-distorted output signal with the enhanced pre-distorted signal and adjusting the enhanced polynomials based on the comparison.