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GaN high electron mobility transistor (HEMT) with advantages of high output power density, high voltage and high output impedance is widely used in microwave communications, radar and other fields. Microwave monolithic integrated circuit (MMIC) with advantages of high operating voltage, high output power, frequency bandwidth, loss of small, high efficiency, small size, anti-radiation is widely used in military and commercial, and it is become the current important pillar of developing varieties of high-tech weapons. But compared with developed countries, MMIC industry in china developed late, and there is a large distance between them. So in this context, a monolithic microwave integrated power amplifier based on GaN is being studied.Based on the principle of designing monolithic microwave integrated power amplifier, the large-signal model of GaN HEMT is built into the ADS software system. Through the L-type matching by lumped elements, an MMIC circuits is established. During the design, the lumped elements are electromagnetic analyzed by HFSS. The impact of lumped elements produced by 2DEG is particular analyzed, and then the structure of device is optimization. Based on the new structure, the size, layout, and alignment of lumped elements are analyzed. The S parameters of them, formed as s2p document, is guided to the ADS, and then used in the simulation and optimization of the circuit system. During the ADS simulation, in order to reduce various parasitic effects of the passive components and improve the circuit performance, the circuit and matching structures are re-optimized and finally a better result is got. Bandwidth of 4-12GHz, output power peaked at 37.8dBm, in-band gain of 7dB, flatness±1dB, power density is greater than 5W/mm, and power added efficiency PAE reached 30.98%. Then the circuit layout is made by L-edit software, relying on the existing GaN HEMT process, the corresponding circuit process is designed, and the key points of the process is analyzed very theoretically.
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