Envelope tracking amplification with reduced slew-rate and bandwidth envelopes

Abstract

This paper presents an Envelope Tracking Power Amplifier whose architecture includes a Hybrid Envelope Amplifier (HEA) and an algorithm to adapt the envelope´s characteristics to the HEA´s limitations. The HEA attempts to combine the high efficiency of a switched amplifier with the wide band capabilities of a linear amplifier. A modified Slew Rate (SR) reduction algorithm cope with the bandwidth and SR limitations of the HEA. On the other hand, the non-linearities introduced by this Envelope Amplifier (EA) and by the dynamic supply are compensated using Digital Pre-Distortion. Results show that these non-linearities are compensable and that the architecture offers higher efficiency figures compared to the conventional linear EA.