75 MHz discrete GaN based multi-level buck converter for envelope tracking applications

The operation, design and implementation are described of a multi-level buck converter for switching frequencies approaching 100MHz together with an isolated high-side driver. The analysis of the converter identifies the trade-offs amongst the number of levels, switching frequency, efficiency, and filter bandwidth, which are key considerations for Envelope Tracking (ET) applications. The results show that this topology is particularly suitable to limit power losses caused by semiconductor output capacitances and common-mode parasitic capacitances as well as to increase the output filter tracking bandwidth. The power loss results are validated through simulation and experimentally using a 30V, 14W two-level prototype and a 30V, 14W five-level prototype operating at 75MHz and built using discrete GaN devices.