Discrete Tunable RF-Power GaN-BST Transistors

In this work the current status of a novel Barium-Strontium-Titanate (BST) based discrete tunable RF-power GaN-HEMT transistor is presented. A p-design prototype is evaluated for tunable networks in a load-pull investigation at 0.9 GHz, 1.3 GHz, and 2.0 GHz. It is shown that the individual GaN-cell BST networks can handle more than 2 W output power but the network losses reduce the drain efficiency by 10...35 percentage points. The BST losses are found to be extremely frequency dependant under power operation but the linearity of the device is dominated by the non-linearity of the transistor itself. Present limitations and development areas of this novel concept are discussed in the work.