QuinStar Technology proposes to develop a 4-watt Solid-State Power Amplifier (SSPA) operating at F-band (106-114 GHz) with a power-added efficiency (PAE) of greater than 30%. This will be achieved by employing two major innovations. First, we are employing state-of-the-art wide bandgap GaN (Gallium Nitride) devices. High power density GaN devices have recently been demonstrated at millimeter-wave frequencies with power densities of 5 to 8 times higher than GaAs and drain efficiencies of 50%. Using these devices in a quasi-switching mode, we are proposing to develop a new high-efficiency MMIC operating at F-band with an output power of one watt and an efficiency of greater than 33%. Secondly, we are proposing to utilize a new low loss, H-tee combining approach to combine 4 of these high-efficiency chips to achieve 4 watts. The net result is a unique combination of high performance devices and innovative power combining. We anticipate that this work will result in an order of magnitude increase in the state-of-the-art of SSPA output power and efficiency at F-band. As a result, we believe this work could be very important for NASA's Astrophysics and Earth Science missions and for W-band radar and communications applications.