Design, Analysis and Simulation of a Low Loss and Compact Size 6-bit DMTL Phase Shifter with a Three-State Unit Cell

Phase shifter is one of the main components of the radar and phased array systems. In this paper, a six bit small size low loss MEMS phase shifter is designed, analyzed and simulated. The proposed phase shifter consists of 17 unit cells and each unit can generate three different phase shifts e.g. 5.625, 11.25 and 22.5 degree. The designed unit cell structure includes a co-planar waveguide transmission line, one MEMS bridge and two metal air metal bridges. The bridge capacitors are electrically in series. The bridges are actuated in three different modes, in each mode the distributed capacitance on transmission line and the phase velocity are changed so that a phase shift is achieved. This design reduces the unit cell numbers from 64 in classic 6-bit phase shifter and 32 in two-state one to only 17 unit cells. Therefore, the overall size of the 6-bit phase shifter is reduced. The designed structure is simulated using ANSOFT HFSS and Intellisuite software. Based on the simulation results, the phase shifter is only 11.2mm in size, the roots mean square (RMS) phase error is 1.35 and average loss is 1.2dB. The compact size, low RMS phase error, low loss and low actuation voltage are the main advantages of the designed MEMS phase shifter.