Research On Key Technology Of Microwave Multifunctional Chip Based On SiGe BiCMOS Process

Phased-array technology has been widely used in military fields such as satellite,airborne radar and ballistic missile.Multifunctional chips for amplitude and phase control is the core component of phased array front end.The multifunctional chip plays a decisive role in beam scanning accuracy,transmitting power,receiving sensitivity and other performance of phased array system.Traditional multifunctional chip is realized by GaAs process,which is not compatible with the silicon-based process,such as digital and analog circuit,and the processing cost is high,so it is difficult to meet the need of low cost in modern application.Since each aperture of the active phased array front end is composed of thousands or even tens of thousands of components,the silicon based process with low cost and high integration will become the preferred technology to meet the requirements of miniaturization,integration,low power consumption and high reliability of the phased array system,which is also the development trend at home and abroad.In this paper,a 4-channel Ka frequency band multifunctional core chip based on GF 0.13 m SiGe BiCMOS process is presented.In order to solve the problem of multichannel integration of multifunctional chip in millimeter wave frequency band,the key technologies of each submodule in the chip are studied.The main contents are as follows:1.In order to solve the problem of gain drop in 32~40GHz full frequency band of the whole system channel,a gain equalization technique is applied to compensate the gain compensation amplifier.Both the “Gain-Boosting” technology and cascode topology is applied to maintain the high gain of the amplifier in millimeter wave band.The gain compensation amplifier has a gain of 9.5~11.5dB in the frequency band,and can provide a positive slope gain curve of about 2dB,and the frequency compensation effect makes the whole system have a good gain flatness.The simulation results show that the singlechannel transmission gain is 17.7~19.6dB,and the receiving gain is 12.0~14.7dB.2.In order to give consideration to both the maximum gain and the minimum noise figure,a “Inductive Source Degeneration” technology is adopted to design the LNA in the channel.The key factors affecting the noise figure of on-chip LNA are analyzed,and the self-customized high Q inductors are designed in the layout to further optimize the noise figure.The simulation results show that the noise figure is less than 3.3dB and the gain is greater than 9.8dB in 32~40GHz.3.Traditional phase-shifting units(high-low pass structures)has high insertion loss and is not conducive to miniaturization.In order to solve this problem,the theoretical analysis of T-type and Pi-type phase-shifting structures is carried out based on the equivalent circuit model.According to the characteristics of different phase-shifting structures,the combination of T-Pi type and high-low pass structure is reasonably used to solve the problem that passive phase shifters have large area with high insertion loss and low phase-shifting precision in millimeter wave frequency band.The results shows that the interpolation loss of the seven bit phase shifter in Ka band is less than 18 dB,and the phase-shifting RMS error is less than 3。.4.The whole chip is considered and analyzed systematically,including the power supply scheme,index decomposition,layout of the chip and isolation technology.The complete integration of analog,digital and RF functions of Ka band four-channel multifunctional chip based on SiGe process is achived.