| A solid state power amplifier (SSPA) over the frequency range of 38-40 GHz is designed. The SSPA is composed of small signal amplifier, drive amplifier and power combining amplifier.Wilkinson power divider and combiner are often used to power combining, but it is not easy to do in domestic technics. Based on domestic technics, a low-loss 3-branch directional coupler(DC), which is easier to achieve, is designed. Using the binary power combing technique, 4-way power divider and combiner are accomplished with 3-branch directional couplers. Ansoft Serenade, the microwave circuit CAD software, is used to design circuits, simulate and optimize. The 4-way power divider is ameliorated, and the degree of magnitude unbalance of its outputs is reduced more. The 4-way power divider-combiner circuit is simulated, and its insert loss is approximately 1.5 dB and both the input and output VSWR are less than 1.2. Proper amplifier chips are chosen to accomplish the design of 4-way power combining amplifier, drive amplifier and small signal amplifier. The power output at 1dB compression could achieve 2W in theory. |
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