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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.
In this paper, 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 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. Analysis showed that a RF MEMS switch could feasibly be designed
with a single pulse waveform and no pull-in instability and achieve comparable results to previous waveform
designs. The switch design could reliably close in a timely manner, with small contact velocity, usually with
little to no rebound even when considering manufacturing variability.
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