Compensation of time misalignment between input signals in envelope-tracking amplifiers

This paper considers a problem of time-misalignment between envelope and RF signals in envelope-tracking amplifiers. We propose two novel time-misalignment compensation methods which are based on the concepts of self-tuning control and model reference control from adaptive control theory. The performance of proposed methods, which we measure by the achievable adjacent-channel power ratio, is compared to the performance of the state-of-the-art method. Simulation results suggest that the time-misalignment compensation which is based on self-tuning structure offers a comparable performance as the state-of-the-art method. On the other hand, the time-misalignment compensation which is based on model reference structure outperforms the state-of-the-art method by 20 dB on the average. Furthermore, compensation with model reference structure appears to be very robust to changes in system parameters.