Bias Tee Design for RF Power Amplifiers and GaN FETs Characterization

This paper presents a method for designing a biastee (BT) specifically tailored to characterize power Gallium Nitride (GaN) Field-Effect Transistors (FETs) and develop power amplifiers (PAs). The approach involves carefully selecting network components to ensure stability for conditionally stable FETs, a crucial factor in FET characterization and PA design. The proposed design methodology was validated by designing two BTs to characterize the CGH40006P GaN FET from 0.1 to 6 GHz. The S-parameters measurements using the custom-fabricated BTs were compared to two commercial BTs: one prone to autonomous oscillation and the other without such oscillation tendencies. This comparison confirms the effectiveness and suitability of the proposed methodology.