A linear-assisted DC-DC hybrid power converter for envelope tracking RF power amplifiers

This paper presents the design of a linear-assisted hybrid DC-DC power converter for envelope tracking RF power amplifiers. To jointly leverage the high efficiency of switch-mode DC-DC converters and the wide bandwidth capabilities of linear regulators, a hybrid power supply topology is employed. It exploits a parallel combination of a switch-mode buck DC-DC converter to provide the average power required by the PA, while a push-pull linear regulator is activated to quickly respond to load transients and for envelope tracking. The proposed power supply was designed with a TSMC 0.35-μm CMOS process. For an input voltage of 3V, the PA supply voltage can be regulated at any voltage level from 0.5V to 2.5V, at a nominal switching frequency of 10MHz. It achieves a maximum efficiency of 91.7% at 500mW.