Dynamic Study of a Capacitive MEMS Switch with Double Clamped-Clamped Microbeams

We study a capacitive MEMS switch composed of two clamped-clamped exible microbeams. We first develop a mathematical model for the MEMS switch where the upper microbeam represents the ground transmission line and the lower one represents the central transmission line. An electrostatic force is applied between the two microbeams to yield the switch to its ON and OFF states. We derive the equations of motion of the system and associated boundary conditions and solve the static and dynamic problems using the differential quadratic method. We show that using only nine grid points gives relatively accurate results when compared to those obtained using FEM. We also examine the transient behavior of the microswitch and obtain results indicating that subsequent reduction in actuation voltage, switching time, and power consumption are expected along with relatively good RF performances. ANSYS HFSS simulator is used in this paper to extract the RF characteristics of the microswitch. HFSS simulation results show that the insertion loss is as low as −0.31 dB and that the return loss is better than −12.41 dB at 10 GHz in the ON state. At the OFF state, the isolation is lower than −23 dB in the range of 10 to 50 GHz

Modeling and design of an ultra low-power NEMS relays: application to logic gate inverters

International audienceIn this work we propose a design based on a nanoelectromechanical relay acting as a logic gate inverter. The proposedinverter is made of a double cantilever nanobeam actuated by a fixed central electrode carrying the input signals. The staticand dynamic behaviors of the ohmic nanoinverter gate are investigated using an electromechanical mathematical modelthat fully incorporates nonlinear form of the electrostatic force and the ohmic contact of the nanobeams’ tip with the fixedoutput electrode. The derived electromechanical model is used for electrical and energy analysis. Simulations are used toconfirm the functionality of the inverter. The analysis of the switching energy showed very low power consumptioncompared to classical CMOS inverters. It is shown that the proposed inverter dissipates only 0.45 fJ to code a ‘‘1’’ logicstateand 0.023 fJ to code a ‘‘0’’ logic-state

Electromechanical variable-capacitance capacitor with four electrodes

A variable-capacitance capacitor having first and second electrodes mobile with respect to each other and third and fourth electrodes insulated from the first and second electrodes, capable of receiving a control signal to vary the relative position of the first and second electrodes in order to vary the capacitance between the first and second electrodes, the capacitor further including a system for controlling the position of the second electrode with respect to the first electrode, the system being arranged so that, for at least one relative position of the second electrode with respect to the first electrode, the position of the second electrode with respect to the first electrode is independent from the voltage between the first and second electrodes

A new type of triboelectric nanogenerator with self-actuated series-to-parallel electrical interface based on self-synchronized mechanical switches for exponential charge accumulation in a capacitor

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Contactless four-terminal MEMS Variable Capacitor for Capacitive Adiabatic Logic

International audienceThis paper reports the design, energy recovery and logical functionality modelling of four-terminal MEMS comb-drive devices for capacitive adiabatic logic (CAL). The proposed electromechanical element consists of the moving mass with two insulated electrodes and two fixed electrodes. The two pairs of fixed and moving electrodes form an input and an output comb-drive capacitive transducers. The voltage across the input port allows us to control the capacitance of the output port. The developed contactless four-terminal design is simulated in Coventor MEMS+® software. In order to speed-up transient simulation of numerous devices in an electrical Spice simulator, the obtained electrical and mechanical characteristics are used to fit our Verilog-A analytical compact model. Spice-simulation results demonstrate CAL logical functionalities using cascadable power clock scheme, i.e. logic states differentiation and cascadability. Also we show that MEMS-based calculation is energy efficient, for example, in a chain of four buffers, 99.1% of the energy transferred to the device is recovered for later use when devices operate at 25 Hz. The non-recoverable energy is mainly dissipated by mechanical damping during the logic state transition from high to low level and can be removed by using retractable power clocks. For this mm-scale device the energy dissipated per operation is in the order of one pJ. This is still far from the energy dissipated by a nm-scale FET transistor, which is of the order of 10's aJ. However, for the contactless design constant electric field scaling is possible and the energy dissipation decreases proportionally to the cube of the size. Finally, the difference between the signal energy and the distinguish energy in MEMS-based adiabatic logic is discussed

MEMS Four-Terminal Variable Capacitor for low power Capacitive Adiabatic Logic with High Logic State Differentiation

International audienceThis paper presents a novel four-terminal variable capacitor (FTVC) dedicated to the recent concept of low power capacitive adiabatic logic (CAL). This FTVC is based on silicon nano/micro technologies and is intended to achieve adiabatic logic functions with a better efficiency that by using field effect transistor (FET). The proposed FTVC consists of two capacitors mechanically coupled and electrically isolated, where a comb-drive input capacitor controls a gap-closing capacitor at the output. To fully implement the adiabatic combinational logic, we propose two types of variable capacitors: a positive variable capacitor (PVC) where the output capacitance value increases with the input voltage, and a negative variable capacitance (NVC) where the output capacitance value decreases when the input voltage increases. A compact and accurate electromechanical model has been developed. The electromechanical simulations demonstrate the ability of the proposed FTVC devices for CAL, with improved features such as high logic states differentiation larger than 50% of the full-scale input signal and cascability of both buffers and inverters. Based on the presented analysis, 89% of the total injected energy in the device can be recovered, the remaining energy being dissipated through mechanical damping. During one cycle of operation, a buffer gate of 10x2.5 µm 2 dissipates only 0.9 fJ

Contactless Capacitive Adiabatic Logic

International audienceCMOS technology allows a femto Joule energy dissipation per logic operation, if operated at optimal frequency and voltage. However, this value remains orders of magnitude above the theoretical limit predicted by Lan-dauer. In this work, we present a new paradigm for low power computation, based on variable capacitors. Such components can be implemented with existing MEMS technologies. We show how a smooth capacitance modulation allows an energy-efficient transfer of information through the circuit. By removing electrical contacts, our method limits the current leakages and the associated energy loss. Therefore, capacitive logic must be able to achieve extremely low power dissipation when driven adiabatically. Contactless capacitive logic also promises a better reliability than systems based on MEMS nanorelays

Capacitive adiabatic logic based on gap-closing MEMS devices

International audienceThis paper presents the energy analysis of capacitive adiabatic logic (CAL) based on gap-closing MEMS devices. CAL uses variable capacitance components instead of transistor elements to have a new balance between on-and off-state losses. Ultra-low power consumption in CAL requires an energy efficient way for charging and discharging of the variable capacitance. First, we investigate "pure" electrical model of the two-terminal variable-gap capacitor and demonstrate that any hysteresis in CV-characteristic leads to losses of the stored energy. Next, we propose the design of a four-terminal gap-closing MEMS capacitive element to implement variable capacitance element for CAL and build its Verilog-A compact model. Further, we analyze the energy transfer and losses within this device during adiabatic charging and discharging. The received results demonstrate that the variable gap devices with hysteresis have a non-adiabatic losses during operation with four-phase power clock. Finally, the cascadability of the signal throw buffer chain is presented