High Power Broad C-band Amplifier Using AlGaN/GaN Based High Electron Mobility Transistors

This work demonstrates the design of a high power broad C-band amplifier using AlGaN/GaN based high electron mobility transistors (HEMTs). The C-band HEMT devices with channel length 400 nm are fabricated using standard nanofabrication techniques. The devices are characterized for DC and RF characteristics. The RF power measurements are carried out using manual load pull set-up. The devices show a unity current gain frequency of 25 GHz and power up to 4.9 W/mm for the desired band. These devices have been used to design a broad C-band 3.50 to 5.75 GHz power amplifier in Keysight Advanced Design Simulation (ADS). The design involves broadband matching using extended L-C network for both inputs and outputs. To increase the output power and compensate for the loss due to non-ideal matching network and passives, we have used a power splitter and power combiner at the input and output, respectively. The PA shows an output power of>8W/mm for the aforementioned band with a gain >6 dB at 28 V through a single stage active devices. The same methodology can be extended for higher power and better gain with multiple stages.