Pulsed RF characterization of envelope tracking systems for improved shaping function extraction

This paper presents a measurement setup for pulsed RF characterization of a buck-converter-based envelope tracking (ET) system. In contrast to continuous wave (CW) measurements, the proposed method allows ET system characterization over its full dynamic range without exceeding the power dissipation safe operating area. It includes the dynamic characterization of the individual subsystems, i.e., the envelope amplifier (EA) and the RF power amplifier (PA) with all signals at their interface. This includes also the non-linear and secondary effects like the EA load-impedance shift. The applicability of the test setup is demonstrated by characterizing a 57 W pulsed peak output power ET system based on a reverse buck converter and a floating-ground RF PA operating at 1620 MHz.