Load-modulated GaN power amplifier implementing tunable thick film BST components

In this work, a novel adaptive broadband power amplifier (PA) design based on barium-strontium-titanate (BST) components for dynamic load modulation (DLM) is presented. The designed PA, driven in class C, makes use of a commercial GaN HEMT, and is intended to operate over 1.8-2.2 GHz with maximum output power of 43 dBm together with high efficiency at maximum output power level. At back-off output power operation, the tunable BST-based output matching network introduces the optimum load impedance for high efficiency. The frequency and input power dependent impedance tunability is realized using a π-structure matching topology based on thick film BST varactors which have a very high breakdown voltage of higher than 500 V.