Research And Design Of W-Band GaN MMIC Power Amplifier

The W-band frequency range is 75-110 GHz,often used in the modern military field,many satellites and radars.As one of the most basic components in electronic system,the power amplifier has high research value.With the continuous progress of semiconductor technology in recent years,gallium–nitride(GaN)as a third generation semiconductor technology,has high breakdown voltage,high electron saturation rate,high thermal conductivity and high cut-off frequency.It is very suitable for the W-band power amplifier production process.Because of the smaller volume and easy to mass production,Monolithic Microwave Integrated Circuit(MMIC)is widely used in the design of power amplifier.At the present stage,the main problems of the W-band amplifier are that the output power,gain and Power-added efficiency of the relevant indicators are too low,which restrict the development of the W-band power amplifier and the application of various electronic systems in the w-band.In order to solve the problem that the gain of W-band amplifier is too small,the method of multi-level cascade is adopted to improve the gain of W-band amplifier in this paper.Aiming at the problem that the output power is too small,power divide circuit and power combination circuit are adopted to improve the output power of the circuit.An improved power divide structure combines the power divide network and the matching network is used in the multi-stage cascade amplifier.Compared with the traditional Wilkinson power divider,the circuit has simple structure,good symmetry.And this method can solve the problem of W-band matching to some extent.To sum up,two W-band GaN MMIC power amplifiers are designed in this paper,in addition,the layout that conforms to the process DRC rules was eventually designed for the actual fabrication.First lying the basic knowledge of the amplifier and the general design methods and steps of making the amplifier in detail,including the principle of multi-stage amplifier,and then the component structure and parameters of GaN process were analyzed in detail,paving the way for the later amplifier design.A single-stage power amplifier with a center frequency of 94 GHz was designed using 4*25um power transistor of the GaN HEMT process.The detailed steps and key points of designing power amplifier are described in detail.The gain of the power amplifier is about 5.2dB.Maximum Power-added efficiency is about 11.87% and 1dB compression point output power is 23.2dBm.Compared with other processes in the indicator of single-stage power amplifiers,we can see that GaN process as the most suitable material for the production of W-band power amplifiers have exceeded other processes.The single-stage power amplifier is also designed to provide a cushion for subsequent multistage power amplifiers.Using the 4*50um and 4*60um power transistors of the GaN process,the cascading operation is carried out on the basis of the single-stage amplifier,which enhances the indicators.To ensure the phase-amplitude consistency,the overall design of the amplifier strictly maintain symmetry to avoid power loss due to phase deviation.The gain of the power amplifier is about 11.271 dB,the maximum Power-added efficiency is about 11.29%,and the output power of the 1dB compression point is 29.271 dBm.The layout which conforms to the process DRC rules was eventually designed for the actual fabrication.Compared with the single-stage power amplifier gain and output power has a significant improvement,through the review of the literature,the indicator also basically reached the W-band GaN amplifier index reported at home and abroad.