QuinStar Technology proposes to develop an efficient, solid-state power amplifier (SSPA), operating at V-band frequencies, for remote sensor applications. Specifically, we propose to develop an 8-W power amplifier with an associated PAE of >40% operating over the 65 to 70 GHz band. This will be accomplished by employing two major innovations. First, we plan to utilize wide bandgap Gallium Nitride (GaN) on Silicon Carbide (SiC) device technology. Operating at a higher voltage (typically 28 V versus 4 V for GaAs), GaN permits power densities which are 5-10 times higher than GaAs. In addition to power density, high-voltage operation results in lower matching and cell combining losses, making these MMICs more efficient. Secondly, we are proposing to utilize a switching mode (Class F) to enhance the device efficiency. While this method has demonstrated PAE levels of >80% at 2 GHz, it has not yet been demonstrated at V-band frequencies. Computer simulations, contained in this proposal, indicate that by using this method, MMIC PAE levels of 50% are possible over the 65-70 GHz band. Finally, we will utilize our high-efficiency, H-tee combiner technology to combine 4 of these chips to achieve 8 W output power across the 65 to 70 GHz band.
NASA employs active sensors for measuring precipitation and clouds, for planetary landing, upper atmospheric monitoring, surface water monitoring, soil moisture and global snow coverage, topography measurement and other Earth and planetary science applications. Many of these are remote sensing applications where prime power is limited and hence sensor efficiency is important. This proposed approach has the potential to increase the sensor (amplifier) efficiency by 10 to 20 percentage points.
Applications for this high-efficiency amplifier technology abound for frequencies above and below this band. These include SATCOM and radar applications. High efficiency is particularly important for airborne applications, such as UAVs and fire control radars, where the prime power is limited. SSPAs used in E-band (71-76 GHz) satellite-based downlink transmitters would benefit from this technology. Other applications include satellite-to-satellite constellation communications links at 60 GHz.