Ku-band And Efficient Synthesis Of High-power Amplifier Design

Power combining technology is a valuable direction of research in microwave and millimeter-wave field. Especially recent several years, increasing high powers of the transmitters are needed for communication, along with the development of space technology. Power combining becomes an available method, because of the low power of common used solid-state devices.Conventional plane circuit combining technology has a limit to the maximal power of combining, because of its high insertion loss and only a few combining ways. These disadvantages have been resolved by the spatial power combining technology, and high efficiency and well extendibility have been achieved. But high power CW and high duty ratio pulse isn't suitable for engineering application for its lack of well heat dissipation.This paper presents a four-ways quasi-circuit power combined solid-state amplifier, which has high efficiency, high gain, well extendibility and excellent heat dissipation, after analyzing lots of domestic and foreign existing power combining technologies. Waveguide E-plane T-junction power dividers and E-plane double microstrip probes transitions were adopted in passive parts. The measured passive combining efficiency was better than 89% from 13.8 to 14.8GHz, so excellent coherence has been achieved between experiment and simulation in HFSS; Two-stage amplified scheme was used in active parts. All about 30dB gain, 45-W Max CW power and±1dB P1dB power fluctuation can be achieved. Tuning every amplifiers chain was added for decreasing the influence towards combining efficiency aroused by fluctuation of the individual channels power amplitudes and phases. Only less than±0.5 dB and±5 deg variation of output RF power can be achieved. The passive combining efficiency within the operating band was measured over 87%, and PAE was up to 22%. Finally, temperature experiment (Max 55℃) demonstrated its stability and well heat dissipation. All indexes of this design reach advanced stage of the world. Practical experience is accumulated for following researches of higher power and broadband combining amplifiers.