High-Frequency, Low-Impact Switching of an RF MEMS Switch Without Pull-In Instability

Jordan E. Massad- Sandia National Laboratory

Faculty Mentor
Ralph Smith - North Carolina State University

Micro-electro-mechanical systems (MEMS) switches for radio-frequency (RF) signals have certain advantages over solid-state
switches, such as lower insertion loss, higher isolation, and lower static power dissipation. Mechanical dynamics can be a
determining factor for the reliability of RF MEMS. The RF MEMS ohmic switch discussed in this paper consists of a plate,
suspended over an actuation pad by four double-cantilever springs. Closing the switch with a simple step actuation voltage
typically causes the plate to rebound from its electrical contacts. The rebound interrupts the signal continuity and degrades the
performance, reliability and durability of the switch. The switching dynamics are complicated by a nonlinear, electrostatic pull-in
instability that causes high accelerations. Slow actuation and tailored voltage control signals can mitigate switch bouncing and
effects of the pull-in instability; however, slow switching speed and overly-complex input signals can significantly penalize overall
system-level performance. Examination of a balanced and optimized alternative switching solution is sought. A step toward one
solution is to consider a pull-in-free switch design. This project aims to determine how simple RC-circuit drive signals and particular
structural properties influence the mechanical dynamics of an RF MEMS switch designed without a pull-in instability. The project’s
approach is to develop a validated modeling capability and subsequently study switch behavior for variable drive signals and switch
design parameters. In support of project development, specifiable design parameters and constraints will be provided. Moreover,
transient data of RF MEMS switches from laser Doppler velocimetry will be provided for model validation tasks.

Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department
of Energy under contract DE-AC04-94AL85000.

Background Material:

  • M.S. Allen, J.E. Massad, R.V. Field, Jr., and C.W. Dyck: Input and Design Optimization Under Uncertainty to Minimize the Impact
    Velocity of an Electrostatically Actuated MEMS Switch
  • David Czaplewski, Christopher Dyck, Hartono Sumali, Jordan Massad, Jaron Kuppers, Isak Reines, William Cowan, and Christopher
    Tigges: A Soft-Landing Waveform for Actuation of a Single-Pole Single-Throw Ohmic RF MEMS Switch
  • Hartono Sumali, Jordan Massad, David Czaplewski, and Christopher Dyck:Waveform Design for Pulse-and-Hold Electrostatic
    Actuation in MEMS
  • Jill Blecke, David Epp, Hartono Sumali, and Gordon Parker: A Simple Learning Control to Eliminate RF-MEMS Switch Bounce