Design of X-band SSPA based on GaN HEMT for telemetry subsystem of near-earth space missions

Abstract

In this paper, the design, and implementation of an X-band, 10 W, Solid-State Power Amplifier (SSPA) based on Hybrid Microwave Integrated Circuit (HMIC) technology using Gallium Nitride (GaN) High-Electron Mobility Transistor (HEMT) dies for near-earth space applications is presented. Designed SSPA is customized for use in suborbital missions and has two stages. We have used narrowband Transmission Lines (TL) class E architecture for designing the proposed SSPA. We have applied the transconductance tuning technique for the first time to a GaN HMIC for achieving the required linearity without any additional circuits. Hybrid optimization helps us for obtaining the best output power, efficiency, and linearity in comparison to other X-band GaN HMICs. We implemented our design with a Rogers 6010 laminate printed circuit board (PCB) on a Cu plate for improving the thermal heat transfer. All the on-chip pads were bonded to PCB using gold bonding wires with 25-µm diameter directly. We obtained 40 dBm and 37 dBm maximum output power in the saturation and 1-dB compression point, respectively. The central frequency of the proposed SSPA is 10,640 MHz with 150 MHz Band Width (BW). It works in EB-class with a 40 V voltage power supply and has more than 40% efficiency in saturation output power (Psat). We obtained two tones Intermodulation Distortion Third Harmonic (IMD3) better than −17 dBc in-band. The active area of the implemented SSPA is 40 mm × 50 mm.