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Microelectromechanical Oscillator-Based Digital Logic. Anthony Yeh EE C235, Spring 2009. Introduction. Today’s Digital Computing Transistor-based (switches that are on or off) The Parametron (1950s) Dr. Eiichi Goto (University of Tokyo)
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Microelectromechanical Oscillator-Based Digital Logic Anthony Yeh EE C235, Spring 2009
Introduction • Today’s Digital Computing • Transistor-based (switches that are on or off) • The Parametron (1950s) • Dr. Eiichi Goto (University of Tokyo) • Digital computing element (analogous to transistor) • Based on interference ofparametric oscillators(instead of switches) • Simpler, cheaper, morereliable than transistors of thetime “The History of Computing Project,” http://www.thocp.net/hardware/parametron.htm
Parametric Oscillation • Parametric oscillator versus driven oscillator • Parametron used parametric oscillation of LC resonators (by periodically varying capacitance) Eiichi Goto, "The Parametron, a Digital Computing Element which Utilizes Parametric Oscillation,” Proceedings of the IRE, 1959
Parametron Binary Logic • Parametric oscillation has two stable states of oscillation • Separated by 180 degree phase shift • Very stable • No drift (only two allowed stable states, energy concentrated in resonant frequency) • Strong force (voltage) required to switch between bistable states (unless oscillation is quenched and then restarted) • Selection of state determined by initial small oscillation • Outputs from multiple Parametrons can be combined to form the input to another Parametron to create logic gates Eiichi Goto, "The Parametron, a Digital Computing Element which Utilizes Parametric Oscillation,” Proceedings of the IRE, 1959
MicroelectromechanicalParametron • I. Mahboob, H. Yamaguchi • NTT Basic Research Laboratories, Japan • Demonstrated binary bit storage and bit flip • GaAs beam (260 x 84 x 1.35 um) • Oscillates in out-of-plane direction • Parametric oscillation • Vary spring constant of GaAs beam through piezoelectric effect • Quantum wells at beam ends concentrate electric fields to achieve efficient actuation I. Mahboob, H. Yamaguchi, “Bit storage and bit flip operations in an electromechanical oscillator,” Nature Nanotechnology, May 2008
Bit Storage and Bit Flip • Parametric actuation (piezoelectric) • Trigger switch (small initial oscillation) I. Mahboob, H. Yamaguchi, “Bit storage and bit flip operations in an electromechanical oscillator,” Nature Nanotechnology, May 2008
Technological Potential • Detailed architecture for Parametron logic already exists • As opposed to other recent mechanical logic devices • Electromechanical oscillators can be scaled to NEMS • Projection: 1um x 100nm oscillator beam • Operation frequencies up to 1GHz • 108 bits/cm2 density • Power for bit flip: 10pW (comparable to CMOS) • Power for stable oscillation: ~0.01pW • Nanoelectromechanical logic-based computers I. Mahboob, H. Yamaguchi, “Bit storage and bit flip operations in an electromechanical oscillator,” Nature Nanotechnology, May 2008