Tunable in-package impedance matching for high power transistors based on printed ceramics

This work addresses tunable matching networks (TMN) for in-package integration of RF-power transistors, fabricated on functional thick film layers of Barium-Strontium-Titanate (BST). The deposition of BST layers is performed in a screen printing process. The TMN is designed to cover the typical GaN-HEMT output impedance range from 7 Ohm to 20 Ohm and transforms it directly to 50 Ohm. The insertion loss varies in a range between 0.4 dB and 1.1 dB, depending on frequency and tuning voltage. Co-simulations, implementing a model of a GaN-HEMT in combination with the TMN were carried out. The performance of the TMN is evaluated and compared to a reference non-tunable matching network with regards to drain efficiency and output power over the frequency range from 0.8 GHz to 3.0 GHz. Simulation results are verified with a system measurement of PA and TMN at 2 GHz in class AB, showing a drain efficiency of 47.1 % and output power of 36.9 dBm.