| With the wide use of millimeter-wave technology in various system platforms, the demand for high-power millimeter-wave solid-state transmitter is becoming increasingly urgent. Millimeter-wave PA has the advantages of small size, light weight, low power supply voltage, long life circle, making it widely applied in microwave and millimeter wave systems such as radar, communication and electronic warfare systems. However, the output power of a single solid-state power device fails to meet application require-ments, which has seriously hampered the development of millimeter-wave transmission systems. In order to obtain higher power output, power combining technology is adopt-ed. Meanwhile, in order to improve the linearity and efficiency of a PA, linearization techniques came into being.This research focuses on K-band millimeter-wave solid-state PA based on spatial power combining technology, in combination with linearization technology to improve the linearity. A PA has been designed to verify the proposed scheme with the following tested performance specifications:operating frequency range:25.5 GHz～26.5 GHz, total gain is greater than 44 dB, output power greater than 4.48 W (36.5 dBm), third-order intermodulation suppression is better than 16 dBc, efficiency of the power combing structure (passive) is greater than 96%, the PA has good performance conformance over a wide operating temperature range of -40℃～85℃.Starting from design specifications, the overall design specifications were decom-posed and refined, a general scheme of the PA is drafted. Firstly, basic principles and common techniques of spatial power combining and linearization technology are stud-ied. Main factors affecting the spatial power combining efficiency is also analyzed in detail. Through computer modeling and simulation, two typical spatial power combin-ing structures, namely waveguide T-section 3 dB power splitter and branch waveguide 3 dB splitter, single-/double-probe waveguide-microstrip mutual transition structures as well as the major factors affecting the performance parameters of the microwave struc-tures mentioned above are studied. Multi-way spatial combining networks are explored in depth via simulation, and test results are in good accordance with simulated results.This thesis studies the design of power supply, distribution and protection require-ments for a multi-way spatial combining PA. To simplify power supply requirements, the PA only uses a single+6 V external power supply, the internal circuits convert it to obtain multiple positive and negative voltages required by the drains and gates of the PA chips. To avoid PA chip damage due to power supply failure, a protection circuit is designed so that when the gate is not biased with appropriate negative voltage, the drain power will be shut-down. A 36 V-6 V DC/DC power supply modules is designed to cut the high-current requirement of a multi-way amplifier module, thus reducing circuit losses. The thesis also studies the effects of temperature drift on the PA performance and proposes a flexible temperature compensation solution. In addition, a detailed thermal analysis of the proposed PA is carried out in order to guide its cooling design. As a result, a reliable cooling solution is proposed.The principle and structure of a linearizor is detailedly analyzed in this thesis. Com-ponents used by the proposed analog linearizor such as microstrip Wilkinson splitter,3 dB bridge, diode non-linear generator are modelled, simulated and optimized.The thesis also explores the engineering issues concerning millimeter-wave PA ma-chining, assembly and production process etc., and provides examples of relevant process documents.Finally, the thesis summarizes the debugging and testing methods of the proposed millimeter-wave PA, such as passive/active S parameter test, small/large signal gain, out-put power and 3rd order intermodulation product test, et. al.; and demonstrates corre-sponding test results. |
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