Contactless RF MEMS switch using PZT actuation

RF MEMS devices are competitive for handling high frequency microwave signals. In comparison to semiconductor devices, the performance of RF MEMS devices is highly linear, minimizing signal distortion. A contactless piezoelectric RF MEMS switch has been designed and simulated. Due to the use of a contactless design based on variable capacitance the reliability issues affecting contacting-type MEMS switches are avoided. The structure is piezoelectrically actuated using a sputtered lead zirconate titanate (PZT) layer. Finite element simulation has been conducted to optimize the structure. Electrical simulation predicts that, by achieving an on-off capacitance ratio greater than 10, isolation will exceed 15 dB over the frequency range from 4 to 15 GHz. Preliminary isolation measurements on fabricated devices without the actuating layer showed 26 dB isolation at 4 GHz, similar to that modeled, although isolation did not decrease by the modeled trend at high frequencies approaching 15 GHz.