A special algorithm based on formerly done messurements and equation optimization is introduced to compensate non linear behaviour of magnetic coils, transformers and other non linear components.

Audio amplifiers suffer from both linear distortion, when only the amplitude or phase changes without adding new frequencies, and nonlinear distortion, which is characterized by the appearance of new frequency components when looking at the harmonic spectra. These nonlinear distortions are usually meant by "distortion" in the audio environment.

To mitigate the problem, signal treatment like high frequency preemphasis and curve correction is applied in many fields, and is useful for compensating the nonlinearities of various components in the signal chain. Since such distortions are common, especially in power amplifiers, NLPD is a worthwhile approach.

Optimizing a wave with predistortion

The technique of predistortion is based performed with modern DSP:

Sample Waves

Output Waves

The signal shown here is shifted in the harmonics so that it can precompensate the behavior of the subsequent stage. This corresponds to phase pre-distortion in the first stage. The amplitude curve is initially retained. In a second step, the signal is linearly distorted, i.e. the amplitude response is changed across the frequency in order to extend the increasing attenuation at higher frequencies. This effectively extends the frequency range of the amplifier. In a final step, the signal is distorted non-linearly, i.e. the 1:1 relationship is changed to compensate for the non-linearity of the amplifier.

Conclusion and Summary

 DSPs can be used to enhance linearity of amplifiers.