A Research On Key Technologies Of Ka-Band Multifunctional Chip Based On Silicon Process

Phased array technology is a very important part of near-orbit communication satellites,fire control / weather radars,and some missile attitude control systems.With the development of the communication industry,the fifth-generation mobile communication system(5G)will be commercialized on a large scale in 2020.The millimeter wave band has become one of the popular bands.However,the transmission loss of the millimeter wave band signal in the air is also greater.It is even more necessary for phased array systems to compensate for the high propagation attenuation caused by atmospheric losses.The multifunctional chip with amplitude and phase control function directly affects the performance of the phased array system.The initial multifunctional chip was basically realized by III-V compound process.The III-V compound process has the advantages of high electron mobility,fast drift speed,and forbidden bandwidth,but it is expensive and cannot be integrated with the baseband / digital chip.This leads to an increase in area.The Si and SiGe processes are inexpensive,and can integrate the baseband and digital parts,which can meet the requirements of low cost and high integration.With the progress of the process,the high-frequency performance gradually meets the application requirements.Therefore,the design of multifunctional chips using silicon-based technology is a development trend at home and abroad.Based on the silicon-based process,this paper has conducted in-depth research on the Ka-band differential phase shifter,and made certain optimization designs for the internal modules of the Ka-band multifunctional chip system.The specific work is as follows:1.In order to suppress the common mode signal interference during signal transmission and reduce the influence of RF parasitic parameters on the performance of the phase shifter,a differential structure phase shifter is designed,and the insertion loss of the traditional high-low phase shifter structure is high.,Low integration and other shortcomings,the embedded switch phase shifter(T-type)structure was modeled and analyzed.According to the characteristics of each structure,it is applied to each phase shift unit.The 180 ° phase shift structure adopts a differential signal conversion structure.The phase difference of 180 ° of the differential signal reduces the area and insertion loss of the phase shift unit.Finally,the phase shifter achieves high accuracy,low insertion loss,and small area.Etc.The test results of the six-bit differential phase shifter are: insertion loss is less than 9.1dB,phase-shifted rms error is less than 6 °,standing wave at each port is less than 1.5,and additional attenuation is less than ± 1.3dB.2.n response to the requirements of the multi-function chip for the switching speed,a single-pole double-throw switch in a multi-function chip system is designed.The seriesparallel structure of FET transistors is adopted,and the single-inductance matching branch is modeled and analyzed.Simulation results show: the insertion loss of the switch is less than 2.7dB,the isolation is greater than 22 dB,and the switching time is less than 3.8ns.3.Aiming at the situation of the gain roll-off of the transistor in the system link and the decrease of the Q value of the passive device,a low-frequency mismatch was adopted for the amplifier to achieve the effect of a positive slope gain;and the phenomenon of high and low temperature gain errors of the amplifier,The PTAT voltage source is used as the bias of the amplifier,so a lower high and low temperature gain error is obtained.In the frequency band of 32GHz-38 GHz,the amplifier gain is greater than 15 dB,which can provide a positive slope gain curve of 1.5dB to 2.5dB,so that the gain flatness of the system link is better,the output 1dB compression point is greater than 7dBm,and high and low temperature The gain error is only 2.5dB.