Miniature RF MEMS switch matrices

A novel miniature-size switching unit is reported for application as the building block of multiport switch matrices. The cell consists of 3 cantilever-beam contact type MEMS devices coupled to CPW transmission lines. A major feature of the proposed switch cell is that in each of the operating states there is only one MEMS switch located in the path of signal inducing a similar loss for all switching states. The construction of the entire system is carried out by a six-mask fabrication process. To minimize the unwanted coupling of the RF signal through the bias lines of MEMS devices, high-resistive phosphorous-doped hydrogenated amorphous silicon (n+ a-Si:H) is selected as a material of choice for the dc bias lines. The switching unit has been employed to build a 4times4 switch matrix measuring 1.45 times 1.45 mm² in dimensions. The system presents an excellent RF performance with the worst-case insertion loss, return loss, and isolation of -1.8 dB, -17 dB and 26 dB up to 40 GHz, respectively.