NC State University

Low-Power, High-Performance MEMS-based Switch Fabric

Presenter: Paul D. Franzon
Co-PIs: Wentai Liu, Michael Steer
GRAs: Bruce Duewer, David Winick, John Wilson, Umut Eksi, John Tucker, Som Paudchury
Department of Electrical and Computer Engineering
North Carolina State University
(919) 515 7351
and in collaboration with MCNC


  • Produce a High Bandwidth Reconfigurable Switch Technology
  • Sustained data rates >> 1 Gbps
  • Low power to reconfigure

    • Goal: One-quarter of equivalent CMOS
  • Low power to transmit data

    • Goal: One-quarter of equivalent CMOS switch
  • Reconfiguration rate O(100 ns)
  • Cheaper than CMOS (about $10/cm^2)
  • Dense -- Goal: 192*192 switch

Also investigate RF and analog applications of technology.

Contactless switch technology based on the Capacitive MEMS Switch

  • MEMS = MicroElectroMechanical Systems (`micromachines')
  • Transmit signals as pulses
  • Build switches out of series capacitors

    • `Up' = low capacitance, Switch open
    • `Down' = high capacitance, Switch closed.
  • Reconfigure switch array electrostatically
  • Flip-mount (or edge mount) Switches to CMOS

Pulse Signaling

Switch Fabrication
  • Encode data as a pulse train, rather than edges.
  • Advantages

    • Don't need contacting switches -- 0.1 pF series capacitor passes signals.
    • Reduces power at high data rates.
    • Reduces noise levels
  • Disadvantages

    • More complex receiver and synchronization
    • Need to characterize signal itegrity and robustness

Capacitive MEMS Switch

4*4 Switch architecture
4*4 Switch architecture

Schematic of one switch
Schematic of one switch

SEM photo of piston array
SEM photo of piston array

Potential Applications

  • Configurable Computing
  • Programmable Interconnect
  • System network routers/switches
  • Video-On-Demand
  • Analog/RF version): Low-cost components


  • Capacitive MEMS switches show potential for delivering low-power, high-bandwidth reconfigurable interconnect structures.
  • Main technical innovations:

    • Pulse signalling.
    • Dense addressable piston (capacitor) array
  • Potential to serve as an RF component too for beam steering, etc.
  • Status:

    • Funded by DARPA and NSF
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