Design And Research Of True-time Delayer Based On RF MEMS Switch

The true-time delayer is an essential signal processing unit in the phased array system,and its main function is to delay the passing signal.The traditional phase shifter has slow phase change speed,high loss,complex drive circuit and poor selectivity.Moreover,due to the large volume and weight of the phase shifter,the electric size of the phase shifter is too large in the RF and microwave frequency band,which will cause serious parasitic effects,so it cannot meet the requirements of the broadband phased array system.In contrast,MEMS time delayers have the advantages of small size,low power consumption and high linearity,which can meet the requirements of miniaturization,wide dynamic range and easy integration of phased array systems.Therefore,a design and study of MEMS true-time delayer is developed in this paper.First,the RF MEMS switch,a key device used in MEMS time delay,is analyzed and designed,and the structure design process is introduced in detail.By analyzing the operating principle and performance parameters of the switch,and selecting low-loss substrate materials and structural metals according to the CPW transmission line design theory,the RF performance of the RF MEMS switch with different upper electrode etched holes is discussed,and the switch upper electrode suitable for the delay timer is selected,and finally the design of the RF MEMS switch is completed.Secondly,the analysis and design of multi-bit true-time delayers are carried out.Starting from the design theory of time delayers,this paper briefly analyzes the characteristics and main indexes of time delayers,analyzes,designs and optimizes the structure of delay units,then designs the overall structure of true-time delayers,and uses simulation software to optimize the RF performance simulation of time delayers,and finally obtains two kinds of real-time delayers for two frequency bands.Finally,the fabrication process technology of real-time delay is studied,and the layout design of MEMS delay fabrication process is carried out by using L-edit software according to the geometric parameters of MEMS switch-based multi-bit real-time delay design,the fabrication process flow of MEMS switch-based delay is designed,and the specific fabrication process steps are described,and finally the RF MEMS switch-based multi-bit real-time The prototype of RF MEMS switch-based multi-bit real-time delay device was obtained.A test system and a miniaturized lifetime test system were built to test the electrical and microwave performance of the RF MEMS switch at room temperature.The test results show that: the driving voltage is 60.1V;the on time of the switch is about 48.4μs and the off time is about 37.8μs;the service life of the RF MEMS switch can reach 10^6 times;in the frequency band of 10MHz～40GHz,the maximum insertion loss of the RF MEMS switch is better than 0.49 d B,the return loss is better than 18 d B,the RF MEMS switch has good microwave performance;in the frequency band of 10MHz～20GHz,the group delay is212.52ps@20GHz,the delay resolution is 1.42ps.