The influence of mechanical shock on the operation of electrostatically driven RF-MEMS switches

A closed-form relationship between the insertion loss, the externally applied mechanical shock and the RF signal voltage of a capacitive RF-MEMS shunt switch is derived. It is shown that, based on this relationship, the minimum required mechanical stiffness of the suspended structure can be calculated. This allows determination of the minimum electrostatic switching voltage in a given process flow. The results are illustrated for specifications regarding shock resistance of electronic equipment as set out in MIL-STD-883. Even under the least severe test conditions, the shocks can affect the insertion loss of RF-MEMS switches, and can provoke self-biasing. This paper gives guidelines to avoid such false operation modes. The method can also be extended to yield the sensitivity of RF-MEMS devices to harmonic vibrations.

[1]  Eric Beyne,et al.  MEMS for wireless communications: ‘from RF-MEMS components to RF-MEMS-SiP’ , 2003 .

[2]  Yuancheng Sun,et al.  Modified Reynolds' equation and analytical analysis of squeeze-film air damping of perforated structures , 2003 .

[3]  V. T. Srikar,et al.  The reliability of microelectromechanical systems (MEMS) in shock environments , 2002 .

[4]  R. Puers,et al.  A physical model to predict stiction in MEMS , 2006 .

[5]  Gabriel M. Rebeiz,et al.  RF MEMS switches and switch circuits , 2001 .

[6]  Angeliki Tserepi,et al.  Fabrication of suspended thermally insulating membranes using frontside micromachining of the Si substrate: characterization of the etching process , 2003 .

[7]  C. Nguyen,et al.  Design of low actuation voltage RF MEMS switch , 2000, 2000 IEEE MTT-S International Microwave Symposium Digest (Cat. No.00CH37017).

[8]  T. Veijola,et al.  Gas damping model for a RF MEM switch and its dynamic characteristics , 2002, 2002 IEEE MTT-S International Microwave Symposium Digest (Cat. No.02CH37278).

[9]  T. Veijola,et al.  Model for gas film damping in a silicon accelerometer , 1997, Proceedings of International Solid State Sensors and Actuators Conference (Transducers '97).

[10]  J. David Logan,et al.  Dimensional Analysis and the Pi Theorem , 1982 .

[11]  S. Brebels,et al.  Modelling of the RF self-actuation of electrostatic RF-MEMS devices , 2004, 17th IEEE International Conference on Micro Electro Mechanical Systems. Maastricht MEMS 2004 Technical Digest.

[12]  T.G.H. Basten,et al.  Transient non-linear response of 'pull-in MEMS devices' including squeeze film effects , 1999 .

[13]  A. B. M. Jansman,et al.  The integration of RF passives using thin-film technology on high-ohmic Si in combination with thick-film interconnect , 2001 .