A Novel Linear MEMS Capacitor With Triangular Electrodes and Nonlinear Structural Stiffness

2008 ◽  
Author(s):  
Mohammad Shavezipur ◽  
Seyed Mohammad Hashemi ◽  
Amir Khajepour
Keyword(s):  
Parallel Plate ◽  
Structural Stiffness ◽  
Tunable Capacitors ◽  
Structural Rigidity ◽  
Novel Structure ◽  
Simple Geometry ◽  
Voltage Change ◽  
Highly Sensitive ◽  
Q Factors ◽  
Structural Layer

MEMS parallel-plate tunable capacitors have high Q-factors and fast responses to the actuation and therefore are desired for RF applications. However, conventional designs have low tuning ratios and nonlinear capacitance-voltage (C-V) responses which are highly sensitive to the voltage change near pull-in. In this research, a novel structure for parallel-plate-based capacitors is introduced. The capacitor has electrodes with triangular shape and uneven supporting beams and is equipped with a set of middle beams which increases the structural stiffness of the capacitor as bias voltage increases. Because the asymmetric design alters the parallelness of the plates, the stiffness of each middle beam is added to the system at a different voltage causing a smooth increment in structural stiffness. To analyze the capacitor and optimize the design, an analytical model is developed to solve the coupled electrostatic-structural physics. The results of numerical simulations reveal that if the stiffness coefficients of supporting and middle beams are optimized, a highly linear C-V response is obtained. Moreover, since the structural rigidity is gradually increased with voltage, the sensitivity of the response to the voltage change is also improved and a higher tunability over 150% is achieved. The proposed design has a simple geometry and can be fabricated by a three-structural-layer process such as PolyMUMPs.

A Novel Highly Tunable Butterfly-Type MEMS Capacitor

2007 ◽  
Author(s):  
Mohammad Shavezipur ◽  
Amir Khajepour ◽  
Seyed Mohammad Hashemi
Keyword(s):  
Electrostatic Force ◽  
Actuation Voltage ◽  
Tunable Capacitor ◽  
Tunable Capacitors ◽  
High Tunability ◽  
Structural Rigidity ◽  
Highly Sensitive ◽  
Capacitance Voltage ◽  
Nodal Displacements ◽  
Q Factors

MEMS parallel-plate tunable capacitors are widely used in different devices such as tunable filters and resonators because of their simple structures, high Q-factors and small sizes. However, these capacitors have low tuning range with nonlinear and highly sensitive capacitance-voltage (C-V) responses. In this paper the development of novel tunable capacitor designs exhibiting highly linear C-V responses, is presented. The designs use segmentation technique to produce lumped flexibility in capacitor’s structure. A numerical model is developed to simulate the behavior of the capacitor. When a actuation voltage is applied, the structural rigidity of the plate produces resistive force which balances the electrostatic force, causes nodal displacements and changes the capacitance. It is shown that by optimizing the shape of segments (from rectangular to trapezoidal) and adding flexible steps located under the segments, a low sensitive linear C-V response could be achieved, while maintaining high tunability. The results of numerical simulation for the capacitors designed for PolyMUMPs process demonstrate that by optimization of the segments shape and structural stiffness a combination of high tunability over 100% and highly linear C-V response is achievable.

Novel Highly Tunable MEMS Capacitors With Flexible Structure and Linear C-V Response

2007 ◽  
Author(s):  
Mohammad Shavezipur ◽  
Seyed Mohammad Hashemi ◽  
Amir Khajepour
Keyword(s):  
Vertical Movement ◽  
Moving Plate ◽  
Rf Systems ◽  
Tunable Capacitors ◽  
High Tunability ◽  
Highly Sensitive ◽  
Capacitance Voltage ◽  
Middle Node ◽  
Low Sensitivity ◽  
Q Factors

MEMS parallel-plate tunable capacitors are widely used in different areas such as tunable filters, resonators and communications (RF) systems for their simple structures, high Q-factors and small sizes. However, these capacitors have relatively low tuning range (50%) and are subjected to highly sensitive and nonlinear capacitance-voltage (C-V) responses. In this paper novel designs are developed which have C-V responses with high linearity and tunability and low sensitivity. The designs use the flexibility of the moving plates. The plate is segmented to provide a controllable flexibility. Segments are connected together at end nodes by torsional springs. Under each node there is a step which limits the vertical movement of that node. An optimization program finds the best set of step heights that provides the highest linearity. Two numerical examples of three-segmented- and six-segmented-plate capacitors verify that the segmentation of moving plate can considerably improve the linearity without decreasing the conventional tunability. A two-segmented-plate capacitor is then designed for standard processes which cannot fabricate steps of different heights. The new design uses a flexible step (spring) under middle node. The simulation of a capacitor with flexible middle step, designed for PolyMUMPs process, demonstrates a C-V response with high tunability and linearity and low sensitivity.

Development of a Linearly Tunable Modified Butterfly-Shape MEMS Capacitor

2008 ◽  
Author(s):  
Mohammad Shavezipur ◽  
Seyed Mohammad Hashemi ◽  
Amir Khajepour ◽  
Patricia Nieva
Keyword(s):  
Actuation Voltage ◽  
Insulator Layer ◽  
Plate Electrode ◽  
Electrostatically Actuated ◽  
Monolithically Integrated ◽  
Tunable Capacitors ◽  
Capacitance Voltage ◽  
Rf Devices ◽  
Fixed Electrode ◽  
Structural Layer

This paper presents a novel geometry and modified structural stiffness for electrostatically actuated MEMS tunable capacitors. The design is based on parallel-plate configuration and four triangular plates are put together to form a butterfly shape flexible moving electrode. Each triangle is suspended by three uneven supporting beams. The capacitor is also equipped with extra beams, called here the “middle beams”, located under the triangles’ corners (nodes). An analytical model is developed to solve the governing equations of a triangular-plate electrode with uneven sides and supporting beams, where the stiffness of the middle beams is gradually added to the system as actuation voltage increases. The numerical simulations reveal that each triangle can be individually tuned up to 150% and the capacitance-voltage (C-V) response is broken into small sections due to added middle beams. Using the model developed in this paper and by design optimization, a linear C-V response is obtained, where the tunability in linear region reaches 100%. The simplicity of the proposed design allows the device to be fabricated using a three-structural-layer process such as PolyMUMPs and could therefore be monolithically integrated with other RF devices and ICs. Moreover, adding additional insulator layer on top of the fixed electrode increases the tunability to over 200% displaying a smooth and low sensitive response.

scholarly journals Quantitative Study of Photoelectric Laser Stimulation for Logic State Imaging in Embedded SRAM

2021 ◽  
Author(s):  
S. Chef ◽  
C.T. Chua ◽  
J.Y. Tay ◽  
C.L Gan
Keyword(s):  
Integrated Circuits ◽  
Sensitive Information ◽  
Laser Stimulation ◽  
Voltage Change ◽  
Current Voltage ◽  
Change Effect ◽  
Highly Sensitive ◽  
Potential Benefits ◽  
Logic State ◽  
Embedded Sram

Abstract The use of optical techniques for attacking integrated circuits (ICs) at the silicon level is increasingly being reported. Although these attacks can be complex to set and require skilled attacker that can access expensive equipment, they are nonetheless very powerful. Among the different applications described in literature, there has been a focus on extracting data directly from embedded SRAM. Such attacks can provide access to highly sensitive information such as encryption keys and bypass various security strategies. An attacker usually exploits one of the several interactions that exist between light and semiconductor to generate an image where content can be directly qualified by the data in memory (Logic State Image – LSI). Thermal laser stimulation (TLS) and laser probing (EOFM-Electro-Optical Frequency Mapping) have been reported in the literature recently but Photoelectric Laser Stimulation (PLS) did not get as much attention. Considering the potential advantages of PLS over other techniques (e.g. lower power requirements to generate current/voltage change, effect can be triggered at shorter wavelength which may lead to an improved spatial resolution), we investigate in this paper if logic state images can be generated with PLS on a variety of devices and do a comparative assessment with state-of-the-art technologies to assess potential benefits and limitations.

A MEMS Tunable Capacitor With Dual Deformation Modes and High Tunability and Linearity

2021 ◽  
Author(s):  
Mahdi Shahi ◽  
Mohammad Shavezipur
Keyword(s):  
Parallel Plate ◽  
Actuation Voltage ◽  
Rf Circuits ◽  
Structural Instability ◽  
Design Parameters ◽  
Tunable Capacitor ◽  
Tunable Capacitors ◽  
High Tunability ◽  
Highly Nonlinear ◽  
Rigid Body Displacement

Abstract MEMS tunable capacitors have applications in tunable filters and RF circuits where high tunability and Q-factor are desired. Conventional parallel-plate tunable capacitors have a highly nonlinear capacitance-voltage (C-V) response and limited tunability of up to 50% due to fundamental limitation and structural instability. In this work, we present a novel design idea for a parallel-plate tunable capacitor that increases the tuning ratio and provides a smoother (more linear) response. The design uses two modes of deformation, rigid-body displacement of a curved moving electrode before pull-in and deforming the plate after pull-in, and exploits nonlinear structural stiffness to improve the linearity (and the tunability) of the tunable parallel-plate capacitor. The capacitor structure is designed such that when actuation voltage is applied, first the beams holding the moving electrode deform, and capacitance increase similar to conventional design up to pull-in. After the pull-in, the top electrode (which has a curved geometry) is deformed and further increases the capacitance, as the voltage increases. The design may provide an overall simulated tunability of more than 380%, and also has a more linear C-V response. The design is modeled and simulated using ANSYS coupled-field multiphysics solver and the effect of different design parameters are investigated. The simulation results show much high tunability and better linearity than conventional parallel-plate capacitors.

A Linearly Tunable MEMS Capacitor With Segmented Electrode and Enhanced Structure

2008 ◽  
Author(s):  
Mohammad Shavezipur ◽  
Seyed Mohammad Hashemi ◽  
Amir Khajepour ◽  
Patricia Nieva
Keyword(s):  
Optimization Problem ◽  
Cantilever Beams ◽  
Structural Stiffness ◽  
Governing Equations ◽  
Flexible Electrode ◽  
Design Variables ◽  
Capacitance Voltage ◽  
Core Idea ◽  
Segmented Electrode ◽  
Structural Layer

This research presents a novel linearly tunable MEMS capacitor with flexible electrode and modified structural stiffness. The capacitor is designed for PolyMUMPs as a standard three-structural-layer fabrication process. The moving electrode is divided into segments interconnected through torsional springs. Under each connecting point (node) two flexible and rigid steps are located. The flexible steps are cantilever beams, and as the bias voltage increases, they touch their corresponding nodes and consequently their stiffnesses are added to the total structural stiffness. This is the core idea of the proposed design to linearize the capacitance-voltage (C-V) response. An analytical model is developed to investigate the behavior of the new capacitor. In this model, the governing equations of the capacitor are numerically solved to obtain the system’s C-V response. An optimization problem with different design variables, such as dimensions of the segments or the beams stiffness coefficients, is solved to maximize the linearity of the C-V curves. The numerical results demonstrate drastic improvement in capacitors performance, where a highly linear C-V response and a maximum tunability of 94% is reached.

A molecular model of low-voltage-activated calcium conductance

1995 ◽  
Vol 73 (6) ◽  
pp. 2349-2356 ◽  
Author(s):  
A. Miller ◽  
B. Hu
Keyword(s):  
Kinetic Model ◽  
Low Voltage ◽  
Molecular Model ◽  
Physiological Role ◽  
Microscopic Mechanism ◽  
Channel Activation ◽  
Potential Oscillations ◽  
Novel Structure ◽  
Voltage Change ◽  
Voltage Dependent

1. T-type or low-voltage-activated Ca2+ channels (IT) expressed in the mammalian thalamus play an important physiological role in the induction of membrane potential oscillations and in the regulation of the timing of synaptic signaling. On the basis of recent molecular studies on Ca2+, Na+, and K+ channels, a structure-kinetic model has been proposed for IT. 2. The model considers that the pore-opening process of IT is governed by three of the four protein domains that are arranged asymmetrically across the membrane plane. The three cytoplasmic linkers connecting individual channel domains serve as inactivation gates. On a membrane voltage change, each domain may engage independently into a sequential, thermodynamically coupled conformational change, thereby causing channel activation and inactivation. 3. A linear Marcov chain reaction with coupled channel activation and inactivation was adopted to test the kinetic feasibility of this trimeric model in a single-compartmental thalamic cell. The differential equations for voltage-dependent rate constants and transitional rates were solved to produce macroscopic T-type Ca2+ current. 4. Our simulation results indicate that this novel structure-kinetic model produces excellent predictions of the macroscopic behaviors of IT, and, more importantly, it provides some new insights into the microscopic mechanism underlying channel recovery.

Design and Modelling of Novel Linearly Tunable Capacitors

2006 ◽  
Author(s):  
Mohammad Shavezipur ◽  
Amir Khajepour ◽  
Seyed Mohammad Hashemi
Keyword(s):  
High Sensitivity ◽  
Variable Stiffness ◽  
Lower Sensitivity ◽  
High Q ◽  
Tunable Capacitors ◽  
High Tunability ◽  
Capacitance Voltage ◽  
Low Sensitivity ◽  
Q Factors ◽  
Very High

MEMS-based tunable capacitors with electrostatic actuation are well-known for their wide tuning ranges, high Q-factors, fast responses, and small sizes. However, tunable capacitors exhibit very high sensitivity near pull-in voltage which counters the concept of tunability. In this research, two novel designs are presented that improve the high sensitivity in capacitance-voltage (C-V) curve. In the first design, the nonlinear deformation of supporting beams is studied to develop a new nonlinear spring. The variable stiffness coefficients of such springs improve the linearity of the C-V curve, and by delaying the pull-in, the maximum tunability is also increased without using complex geometries. In the second design, an asymmetric non-parallel-plate capacitor is introduced, in which the C-V response has lower sensitivity at high voltages. The design concept can be applied to highly tunable capacitors to improve the sensitivity and maintain high tunability. The numerical results demonstrate low sensitivity and high linearity and tunability for the new designs.

A Flexible Accelerometer System for Human Pulse Monitoring

2014 ◽  
Vol 1690 ◽  
Author(s):  
Yuanfeng Zhang ◽  
Woo Soo Kim
Keyword(s):  
Parallel Plate ◽  
High Sensitivity ◽  
Cost Effective ◽  
The Body ◽  
Light Weight ◽  
Capacitive Sensing ◽  
Direct Printing ◽  
Voltage Output ◽  
Highly Sensitive ◽  
Weight Sensor

ABSTRACTHere we introduce a cost-effective and highly sensitive flexible accelerometer system, which can sense human pulse by detecting the pulsation. The accelerometer employs capacitive sensing with a structure of two parallel plate electrodes with the optimally designed top electrode pattern in order to achieve high sensitivity. This flexible light-weight sensor is fabricated by direct-printing of silver nano-inks on pre-patterned flexible paper substrates. When the accelerometer is attached to the body surfaces: neck, inner elbow, or any other pulsation point, accurate pulse rates are obtained by reading out the voltage output signal.

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