Thick-Film MIM BST Varactors for GaN Power Amplifiers with Discrete Dynamic Load Modulation
IEEE MTT-S Int. Microw. Symp. Dig., Honolulu, USA, Jun. 4-9, pp. 281-284 (2017).
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Due to their extremely low static current consumption, varactors based on BST are perfect devices for realization of tunable and re-configurable components. This work presents fully screen-printed MIM thick-film BST varactors that are used to tune the load impedance for GaN HEMTs. The varactor tuning voltage is supplied in discrete steps using a high-speed GaN-based modulator. Modulated measurements with LTE and WCDMA signals show, for the first time, the functionality of a BST-based load modulation system and the power consumption of the load-modulation in dynamic operation. Using discrete dynamic load modulation, an average PAE of 27.3% was measured for the LTE signal with an ACLR below -45 dB.
1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, 12489 Berlin, Germany
2 Technische Universitaet Darmstadt, Institut fuer Mikrowellentechnik und Photonik, 64283 Darmstadt, Germany
BST, ferroelectrics, gallium nitride, HEMTs, load modulation, power amplifiers, varactors.