Digital closed loop design for wideband envelope tracking system

摘要

In this paper, we will show two methods of digital closed loop envelope tracking systems for high bandwidth communication systems, tested on wifi 80 MHz signals (11ac) in high level simulation platform (matlab & simulink). We will present the challenges of high frequency digital DC2DC converter for envelope tracking (ET) as load modulation wide digital controller loop and noise and saturation in the loop, and multilevel ET based on several high BW digital low dropout (DLDO) voltage regulators, and examine the differences in terms of the challenges and coping mechanisms each one holds. We will show that although the existing highly non-linear PA in our system, both architectures provide the solution in terms of band edge (BE) mask limitation, with efficiency of ~80% for the ET full driver. All components in both architectures are fully digital and synthesizable, which has a big advantage compared to analog options in efficiency noise and size, and of course assures robustness and flexibility.