High Efficiency, High Bandwidth Switch-Mode Envelope Tracking Supply Modulator

This paper presents a novel amplitude modulator concept for envelope tracking power amplifiers, which provides maximum efficiency in the lower output voltage ranges, thus nicely matching the probability density function of modern high-peak-to-average-power baseband signals. It can easily handle modulation bandwidths in excess of 300MHz. Furthermore, it operates purely in switch mode, unleashing great potential for overall efficiency. A first hardware implementation reaches around 60 % conversion efficiency and over 84 % when the output voltage is at its minimum value.