QuinStar Technology proposes to develop an efficient, solid-state power amplifier (SSPA), operating at V-band frequencies in support of NASA Earth and planetary science applications. This proposal addresses the critical need for high-efficiency, millimeter-wave amplifiers used in absorption radar for remote pressure sensing to improve weather models. Specifically, we propose to develop a pulsed power amplifier with a minimum duty cycle of 25% operating over the 65-71 GHz band. The output power of the SSPA is specified to be more than 10 Watts throughout the band of 65-to-71 GHz with an associated PAE of more than 30%. The efficiency and power goals of this program will be realized by employing a combination of state-of-the-art (SOA) device technology, innovative circuit design, and power combining techniques.
Simulations of the MMIC design using 90 nm GaN HEMT from Qorvo indicate that the power-added-efficiency (PAE) of 33% in the MMIC can be achieved across the band from 65 to 71 GHz with an associated output power of 2.8 W. We propose to realize the specified SSPA power level (>10 W) with high-efficiency waveguide circuit combining techniques. A high-efficiency, 4-way H-tee combiner network was designed in the Phase I program to combine four MMICs and deliver an output power of more than 10 Watts. The combining efficiencies of the 4-way H-tee combiner is simulated greater than 94% in the band of interest, which translates into a PAE of 31% in the SSPA. The compact size and light weight of the SSPA are projected 2.2 x 2.0 x 1.0 inches and 6 oz. respectively, which make it suitable for application to CubeSat/SmallSat platforms.
The main application for NASA is absorption radar for pressure sensing. The remote sensing measurement of pressure will drastically improve the numerical weather models and help solve one of the “most important questions” mentioned in the decadal survey. NASA has had proposals of surface barometric pressure sensing based on the demonstration of this technology. Further, NASA employs satellite-based, active sensors for Earth and planetary science applications, which would benefit from this high-efficiency SSPA approach.
Applications for this high-efficiency amplifier technology abound at other government agencies for frequencies above and below V-band. These include SATCOM and radar applications for all military services. There is an initiative within the FCC to expand the unlicensed frequency spectrum in V-band (57-64 GHz) to include the 64-71 GHz band where the technology is directly applicable.