Research On Ka-band Power Amplifier MMIC

With the rapid development of science and technology,people have higher and higher requirements on information and communication,and have put forward higher requirements on the speed of communication and information capacity.And due to the increasingly scarce spectrum resources,people have shifted their attention to the millimeter wave.Ka band with its wide bandwidth,less interference,equipment,small size has become a hot research and application.Whether it is phased array radar,electronic countermeasures,or satellite communications,power amplifiers are an important part of them,Its performance directly affects the performance of the entire system.so the study of the power amplifier is essential.The microwave monolithic integrated circuit(MMIC)is a new type of microwave circuit.Unlike conventional hybrid integrated circuits,it mainly uses active devices and passive components directly on the same semiconductor substrate through photolithography or sputtering techniques,to achieve a fully functional microwave circuit.Its operating frequency can usually be from the low end of the microwave to the high end of the millimeter wave or even the terahertz band.Compared with the traditional hybrid microwave integrated circuit,the microwave monolithic integrated circuit has high reliability and service life because it adopts an internal matching structure and is basically stable after the circuit processing is completed.At the same time,microwave monolithic integrated circuits can be repetitively produced at a time and have strong reproducibility.Not only that,microwave monolithic integrated circuits also have the advantages of small circuit area,operating frequency bandwidth,and so on.However,since the microwave monolithic integrated circuit can not be changed after being taped,it also poses no small challenge to designers.Based on the above reasons,this paper designs two Ka-band monolithic power amplifiers,one of which is based on the cutting-edge third-generation semiconductor GaN HEMT process.GaN HEMTs have the advantages of large power capacity,high work efficiency,and are ideal for power amplification.However,the disadvantages of its immature process,inaccurate model,and high price limit its application.The other one uses a more mature GaAs process.Its main advantages are mature technology,accurate model,and high cost performance.However,the power density is not as high as that of GaN,and the transistor breakdown voltage is small.Therefore,when a high-power device is manufactured,multiple transistors are often required.Perform power synthesis,making the design circuit complex and excessive loss.This article first analyzes the transistors used in the design,determines the transistors that are suitable for the circuit's specifications,and selects the appropriate DC bias to ensure that the transistors operate at their best.On the circuit side,load traction,matching design,stability design,amplifier circuit design and power synthesis design were performed,and two Ka-band amplifier circuits were completed.Finally,the design of GaN power amplifier indicators: frequency of 32 ~ 38 GHz,gain greater than 18 dB,input and output standing wave is less than 2,the efficiency is greater than 30%,the saturated output power of 32.5dBm,chip size is 2.85mm×1.45 mm.Design GaAs power amplifier indicators are: frequency of 32 ~ 38 GHz,gain greater than 15 dB,input and output standing wave is less than 2,the efficiency is greater than 20%,the saturated output power to 30 dBm,chip size is 2.85mm×1.45 mm.By comparing the two power amplifiers,it can be seen that GaN power amplifiers are far superior to GaAs power amplifiers in terms of performance and circuit size.The new GaN technology has great advantages and application prospects in the design of power devices.