High-Efficiency, Ka-Band Solid-State Power Amplifier Utilizing GaN Technology

QuinStar Technology proposes to develop an efficient, solid-state power amplifier (SSPA), operating at Ka-band frequencies, for high data rate, long range space communications. Specifically, we propose to develop a 20 W power amplifier with an associated PAE of 60% operating over the 31.5 to 34 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 20-28 V versus 4-5 V for GaAs), GaN permits power densities which are 5-10 times higher than GaAs or InP. In addition to the 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 Ka-band. Computer simulations, contained in this proposal, indicate that by using this method, PAE levels ranging from 65% to 80% are possible. This was verified by device models from three different foundries. Finally, we will utilize our high-efficiency, H-tee combiner technology to combine 4 of these chips to achieve 20 W output power.