A digital predistortion assisted hybrid supply modulator for envelope tracking power amplifiers

•The proposed architecture uses a parallel combination of class D and linear stage topology for the modulator.•The presented architecture incorporates digital controller for the linear stage.•The proposed digital modulator output inductor is lower than other reported supply modulator at the same output power.•The given approach improves static efficiency up to 9% in comparison to conventional one-phase and two-phase modulators at the same condition in terms of output inductor due to lower switching frequency.•The presented method is able to reduce output switching noise ripples up to 10 MHz input signal bandwidth, at the condition of low inductor size.•The low inductance property of the presented architecture will improve large signal behavior and reduce the ripples at transition points, which results in better linearity.

In this paper, a novel digital predistortion assisted supply modulator is presented. The proposed modulator is suitable for envelope tracking power amplifiers. In this topology, a digitally controlled linear power amplifier is used to compensate the switching noise ripples of the switching modulator. The proposed structure is evaluated with a 0.18 µm CMOS process technology. The results show up to 9% static efficiency improvement in comparison with previous one-phase and two-phase architectures. It is shown that for a 5 MHz WiMAX signal with a 6.7 dB PAPR at 26.8 dBm output power, a maximum average efficiency of 73.5% is achieved in the proposed design.