C-Ku band 120% relative bandwidth high efficiency high power amplifier using GaN HEMT

This paper reports on a GaN HEMT (gallium nitride high electron mobility transistor) HIC (hybrid integrated circuit) high power amplifier, which features high efficiency over C-Ku band 120% relative bandwidth. It was found that the output impedance of a transistor under high efficiency operation can be modeled by parallel circuit of R and C. In the circuit design, BPF (band pass filter) configuration is employed, where parasitic capacitance of the transistor is utilized as a part of BPF matching circuit. Hence broadband matching was successfully obtained. A C-Ku band GaN HEMT HIC amplifier was manufactured and measured at 30 V drain voltage. More than 4 W output power and 18% PAE (Power Added Efficiency) were obtained over 120% relative bandwidth. This result is state-of-the-art high efficiency for GaN HEMT HIC amplifier with more than 100% relative bandwidth.