Ultrafast Tracking Power Supply With Fourth-Order Output Filter and Fixed-Frequency Hysteretic Control

A practical solution is presented for the design of a non-isolated dc/dc power converter with very low output ripple voltage and very fast output voltage step response. The converter is intended for use as an envelope tracking power supply for a radio frequency power amplifier (RFPA) in a TETRA enhanced data service (TEDS) base station. A simple and effective fixed-frequency hysteretic control scheme for the converter (buck with fourth-order output filter) is developed and analyzed. The proposed approach is verified experimentally by a 500 W output prototype, capable of delivering any voltage in the range of 10-30 V within 10 mus with 10 mVpp of output ripple and efficiencies in the 88%-95% range.