GaN Class F Power Amplifier for Klystron Replacement

The klystrons used to drive cryomodules at JLAB and other accelerator facilities are relatively inefficient and becoming obsolete, as the RF world has been progressively converting to solid state technology. The JLAB upgrade program requires a ~8 kW, 1497 MHz amplifier operating at 55-60% efficiency, and 8 kW CW power to replace the existing 340 klystrons. Capital and operational costs over the lifetime should be favorable vs. the klystron costs. These challenging requirements are beyond what is currently available on the market. B. Technical Approach This project will develop a solid state replacement based on high electron mobility GaN transistors in a Class-F amplifier with precise in-phase coaxial combiners and highly efficient step-down conversion based on an invertor with novel high voltage insulated-gate bipolar transistors. A water cooling system conformal to the dividing-combining architecture enables optimal performance conditions and long lifetime. High reliability and convenient maintenance of the architecture is provided by the so-called graceful degradation feature: failure or malfunction of one (or even more) transistors in the output array will not cause shutdown of the entire unit. C. Phase I Plan In Phase I, the 8 kW solid state amplifier will be designed and two key component mockups will be fabricated and tested: the F-Class high efficiency power amplifier and the multi-way divider. D. Commercial Applications and Other Benefits The applications include both superconducting and normal conducting accelerator facilities such as free electron lasers (FELs), industrial and medical accelerators, radars, mobile weapon systems, wireless communications, air traffic control and surveillance, wireless gadget charging, microwave chemical and plasmatron technological reactors.