| Millimeter wave power amplifier is the key component of radio frequency electronic system for military use. This project mainly focuses on researching and designing this kind of chip, exploring broadband integrated circuit with high power output ability. GaAs pHEMT power FET model, which is supplied by foundry, is used during design process. The whole design process included choosing the basic form of circuit, evaluating thermal condition of microwave FET, schematic design, electromagnetic simulation of circuit layout and layout design.First of all, the author conscientiously researched on the present MMIC's technology, development, characteristics and design methods. After comparing different MMIC technology, the author chose 0.25μm gate-length GaAs pHEMT as the active devices for this design. Then in order to ensure the reliability of circuit, the author conducted evaluation the design plan in the beginning and used finite element method to simulate the temperature of gate channel. The circuit inside the chip is a four-stage and eight-way power amplifier, which is design on the basis of microwave power amplifier. The pHEMT transistor is set to operate at class A. The simulation results of bias circuit, matching circuit, power combiner and power divider meet the requirements on the whole. After optimization of connecting the above parts, the layout of circuit was adjusted by electromagnetic simulation. Finally, the layout for chip manufacturing is generated according to the dimensions after electromagnetic simulation with area 3.2mm×3.5mm. When 17dBm signal is input, the simulated power amplifier can generate 14.5dB gain above at 30GHz-40GHz with 32.5dBm output power at 30GHz-39GHz and approximately 10%PAE. |
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