Design and Analysis of analog and 4 bit RF MEMS Phase Shifter

Abstract

"In this thesis, analog and digital X-band phase shifters have been designed for the application in radar technology and missile controlling. All basic design designing technology of digital phase shifters have been defined with their design equations. In the first section design an analog phase shifter using vector modulator method and simulated in ADS(Advanced Design Software) .Modified structure of lange coupler with high coupling factor ,biphase modulator using casecad of high coupling baluns,voltage variable attenuators and willkinson power combiner are used to design an analog phase shifter.The simulation results of analog phase shifter shows that insertion loss(S21) lies between 6 to 9dB and return loss(S11) is greater than 15dB in the desired frequency range 8-12GHz. The phase error for each phase shift state is in the range from +5? to -5?. Due to high coupling and modified biphase modulator, this phase shifter gives better insertion loss(S21), return loss(S11) and low phase compare to presently available phase shifters modules. In second section, Design and a X band 4-bit digital phase shifter using MEMS(Micro Electro Mechanical System) SP4T switch and microstrip transmission line. Each single pole four throw(SP4T) switch is used to switch between two different length paths, first is reference path and second is delayed path. 4 contact type cantilever beam series MEMS switches are used to designEach MEMS SP4T switch. In this design of MEMS phase shifter we use 4 SP4T switches, therefor we need 16 contact type cantilever beam series MEMS switches. Schematic design of the phase shifter is put forward. Details of this phase shifter design and components such as SP4T switch and phase delayed lines are put forward . The simulation results of SP4T switch shows that insertion loss and return loss is -36dB and return loss is -0.12dB at the desired frequency 10GHz, and the simulation results of 4 bit MEMS phase Shifter shows that better insertion loss(S21) which is less than 0.4dB and better isolation loss(S11) which is greater then 14dB. The advantages of RF MEMS phase shifter are low insertion loss, high return loss(high isolation and less reflection) and low power dissipation."