Wireless Communications

Miniaturized Distributed MEMS Impedance Matching Networks

Due to the desire of using a single antenna to cover a wide range of wireless communication standards, a tunable impedance matching network is required. This modern impedance matching network should provide large impedance matching abilities, such as low loss, small size and low price. Many reconfigurable impedance matching networks have already been realized based on semiconductor devices. However, these designs suffer from the high power consumption and unwanted intermodulation products. Current development is more focused on the impedance matching networks using MEMS technology because of their low insertion loss and power consumption. Unfortunately, these designs cannot provide a satisfied impedance coverage on the smith chart in low band wireless communications unless they occupy a quite large area. To improve the impedance matching ability with a reasonable size, the electrical length of some slow-wave structures as the transmission line is investigated for reducing the system operating frequency compared to traditional coplanar waveguide (CPW). On the base of this idea, new DMTLs are desired for improving the impedance coverage with a compact size in wireless communication band.

The proposed SW-DGS transmission line is a combination of SW and DGS structures implemented on a CPW line.

mems_picture1

The lower the uniformity factor is, the more uniform is the impedance distribution. Hence this proposed structure provides a more uniform distribution with the same physical length or the structure requires a smaller size for achieving the desired impedance coverage on the Smith chart compared to other DMTL structures up to 10 GHz.

mems_picture2

 
Publications:
 
  1. Y. Chen, and D. Manteuffel, "Distributed MEMS Impedance Matching Network Using a SW-DGS Technique", In Antennas Propagation Conference, 2012. LAPC 2009. Loughborough., nov., 2009. , pp. 50 -56.
    [Abstract]
     
    A novel distributed Micro-Electro-Mechanical-Systems (MEMS) impedance matching network is presented in this paper. This impedance matching network is based on DMTL (Distributed MEMS transmission line) having periodically loaded MEMS switches on a coplanar waveguide (CPW) transmissionline. In order to miniaturize the physical size of the DMTL, a combination of a slow-wave (SW) structure and defect-groundstructure(DGS) is utilized. As a result, the distribution of theimpedance coverage on the Smith chart can be improved for thelimited physical length or reducing its sizefor a certain desiredimpedance distribution can be achieved. The parameter values ofthe equivalent circuit of the proposed structureareextractedfrom numerical simulation results using the FDTD simulatorEMPIRE and are implemented for the calculation the uniformity factor to describe the uniformity of the impedance distributionon the Smith chart.
    [BibTeX]
     
    @inproceedings{,
      author = {Chen, Yi and Manteuffel, D.},
      title = {Distributed MEMS Impedance Matching Network Using a SW-DGS Technique},
      booktitle = {Antennas Propagation Conference, 2012. LAPC 2012. Loughborough},
      year = {2012},
      pages = {},
      doi = {}
    }

  2. Chen, Y. and Manteuffel, D. , "Miniaturizing of a Distributed MEMS Impedance Matching Network,", Antenna Technology (iWAT), 2013 International Workshop on , vol., no., pp.303,306, 4-6 March 2013. DOI 
    [Abstract]
     
    This paper shows a Micro-Electro-Mechanical-Systems (MEMS) impedance matching network based on a distributed MEMS transmission line (DMTL) for wireless communication devices operating in the frequency range from 1.8 GHz to 3.6 GHz. In the proposed design, the capacitive MEMS switches are periodically located on a meandered slow-wave (SW) structure, whose slow wave effect is analytically calculated to reduce the minimum operating frequency of the network. Using this demonstrated transmission line, the size of the impedance matching network is minimized while providing a good impedance matching performance in terms of impedance coverage on the Smith chart.
    [BibTeX]
     
    @INPROCEEDINGS{6518353,
    author={Yi Chen and Manteuffel, D.},
    booktitle={Antenna Technology (iWAT), 2013 International Workshop on},
    title={Miniaturizing of a distributed MEMS impedance matching network},
    year={2013},
    pages={303-306},
    keywords={impedance matching;microswitches;radiocommunication;slow wave structures;transmission lines;DMTL;SW structure;Smith chart;capacitive MEMS switches;distributed MEMS impedance matching network;distributed MEMS transmission line;frequency 1.8 GHz to 3.6 GHz;impedance coverage;impedance matching performance;meandered slow-wave structure;microelectro-mechanical-system;slow wave effect;wireless communication device},
    doi={10.1109/IWAT.2013.6518353},
    }