A switched mode envelope tracker for polar EDGE transmitter

Design and implementation of an envelope tracking switched-mode power supply (SMPS) for polar EDGE transmitter is described in this paper. The objectives are to achieve high efficiency and high fidelity tracking as well as low interferences according to the EDGE spectral mask restrictions, while providing approximately constant signal propagation delay for easy compensation in the phase-modulation path. Simulation and experimental results are shown for a closed-loop PWM buck converter switching at 4.3MHz, using a compensator that results in the overall Bessel type low-pass transfer function.