A Compact Low-Loss 6-bit DMTL Phase Shifter Using a Novel Three-State Unit Cell

In this paper, a novel small-size, low-loss 6-bit MEMS phase shifter is designed, analyzed, and simulated. The proposed structure includes 17 unit cells, and each unit cell can generate three different phase shifts (i.e., 5.625-, 11.25-, and 22.5-degree phase shifts). The designed unit cell consists of a coplanar waveguide transmission line, a MEMS, and two-pair metal–air–metal bridges. The bridge capacitors are electrically in series and are actuated in three different modes. In each mode, the distributed capacitance of the transmission line and the phase velocity are changed to achieve a phase shift. As the novelty of this design, the number of unit cells is reduced from 64 (which is the case in a conventional 6-bit phase shifter) to only 17. Therefore, the total length of the 6-bit phase shifter is considerably reduced. The designed structure is simulated using Ansoft HFSS and IntelliSuite. Based on the simulation results, the lateral size of the phase shifter is only 8.5 mm; the root-mean-square (RMS) phase error is 1.35, and the average loss is 1.2 dB. A step-by-step fabrication process is also proposed for designing the DMTL phase shifter. The designed phase shifter can be easily scaled to other frequencies for radar and satellite applications that require more bits.