Optimized envelope tracking power supply for Tetra2 base station RF power amplifier

• Published in: 2008 Twenty-Third Annual IEEE Applied Power Electronics Conference and Exposition pp. 777 - 783
• Main Authors: Hoyerby, M.C.W., Andersen, M.A.E.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01-02-2008
• Subjects: Base stations; Buck converters; Clocks; Optimization methods; Power amplifiers; Power supplies; Radio frequency; Radiofrequency amplifiers; Sliding mode control; Switching frequency
• ISBN: 9781424418732; 1424418739
• ISSN: 1048-2334; 2470-6647
• DOI: 10.1109/APEC.2008.4522809

An ultra-fast tracking power supply (UFTPS) for envelope tracking in a 50 kHz 64-QAM Tetra2 base station power amplification system is demonstrated. A simple method for optimizing the step response of the PID+PD sliding-mode control system is presented and demonstrated, along with a PLL-based scheme for locking the switching frequency to an external clock. High UFTPS efficiency (up to 95%), very low ripple (5 mV pp ) and a fast step response (10 mus) are obtained from a single-phase buck converter with a 4 th -order output filter. This ripple performance is demonstrated to be critical in the considered application. Also demonstrated is the effect of non-zero UFTPS output impedance on envelope tracking performance. At 13 W average (156 W peak) RF output, a reduction of DC input power consumption from 93 W (14% efficiency) to 54 W (24% efficiency) is obtained by moving from a fixed RF power amplifier supply to envelope tracking.