Analysis, design and experimental evaluation of sub-THz power amplifiers based on GaAs metamorphic HEMT technology

The interest for devices operating in the millimeter-wave range (30-300 GHz) and submillimeter-wave (sub-mmW) range (above 300 GHz) is increasing due to the advantages they provide such as compactness, low weight, broad bandwidth, and the capability to penetrate dust, smog and adverse weather conditions. Compact and broadband single-chip solid state power amplifiers (SSPAs) at sub-THz (0.1-1 THz) frequencies have a decisive impact in many applications including: instrumentation, high-resolution imaging radar and high-data rate communication. Significant improvements in high-speed transistor technologies, such as the 50 nm and 35 nm GaAs metamorphic high electron mobility transistors, enable the realization of SSPAs in the sub-THz regime. However, they present some issues, such as low breakdown voltage, high parasitic effects, and high losses. This work investigates the potential of power amplifier (PA) topologies based on stacked field effect transistor (stacked-FET) configurations and the design of novel low-loss dividers and couplers to overcome these difficulties. As a result, the first experimental demonstrations of PAs based on stacked-FET topologies up to the onset of the sub-mmW range are presented.