Low Pull-in-Voltage RF-MEMS Shunt Switch for 5G Millimeter Wave Applications

P. Ashok Kumar,K. Srinivasa Rao,B. Balaji,M. Aditya,N. P. Maity,Reshmi Maity,Santanu Maity,Ameen El Sinawi,Koushik Guha,K. Girija Sravani 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.6

RF MEMS switches have been employed in many commercial and defense applications due to their high potentiality at microwave and millimeter wave frequencies. In this paper, an RF MEMS shunt switch is designed with perforations and without perforations and simulated using iterative meanders for millimeter wave 5G applications. The proposed iterative meander offers a low spring-constant of 0.68 N/m and reduces the pull-in-voltage upto 1.8 V. The proposed perforated switch design is more reliable which operates with less transition time of 11.2 μs with a quality factor of 1.69. The switch possesses high capacitance ratio of 63. During ON condition, the switch shows low insertion loss of − 0.24 dB at 41 GHz and high isolation of − 46.7 dB at 38 GHz. The performance of the switch is analyzed by simulating it using COMSOL Multiphysics 5.2v (FEM tool). The obtained simulation results shows close approximation with the theoretical results and the switch is efficiently used for 5G millimeter wave applications.

Design of Single Cell Membrane Shape and Array Configuration for MEMS Based Micromachined Ultrasonic Sensor to Improve the Performance: A Three Dimensional Model Characterization

Reshmi Maity,N. P. Maity,Srinivasa Rao Karumuri,Girija Sravani,K. Guha 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.6

The output acoustic energy of a capacitive micromachined ultrasonic transducer (CMUT) can be enhanced by adjusting its membrane structure. In this paper three dissimilar membranes shapes of CMUT: circular, rectangular and hexagonal, were aimed and 3D finite element method simulated using adaptive meshing technique. The displacement as well as strain and stress outputs for a single membrane and an array of four membranes on a single substrate were obtained. The simulated results are supported by analytical modeling. A static bias of 40 V and a signal of amplitude 100 mV are employed. A pressure of 8603.98 N/m 2 resulting in a force of 16.894 μN was applied at the membrane. Fixtures were provided on every possible face of the structure except the face 1 (membrane). The outcomes showed that the membrane displacement is highest for a circular geometry under same uniform pressure and area of vibration. Moreover as the distance between the elemental membranes increases the displacement decreases for circular and hexagonal membranes while the reverse behavior is observed for rectangular membranes.

Effects of Hafnium Oxide on Surface Potential and Drain Current Models for Subthreshold Short Channel Metal–Oxide–Semiconductor-Field-Effect-Transistor

N. P. Maity,Reshmi Maity,Subir Dutta,Subhasish Deb,K. Girija Sravani,K. Srinivasa Rao,S. Baishya 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.3

Surface potential and drain current models for a physically based double halo metal–oxide–semiconductor-fi eld-eff ect-transistor(MOSFET) are reported. The proposed models have been established in sub-threshold mode of MOSFET operation. The depletion layer depth used in the pseudo two dimensional Poisson’s equation comprises the effect of two symmetrical pocket implantations at both the ends of the channel region. In this effort, improvement in the investigation is brought in by taking lateral asymmetric channel owing to non-uniform doping. The conventional silicon-dioxide (SiO2) material is replaced with a promising high-k dielectric material hafnium oxide (HfO2) to analyze the surface potential and drain current models. Analytical results have been compared using Synopsys technology computer aided design (TCAD). Excellent conformities between the analytical models and simulations are observed.

Fringing Capacitive Effect of Silicon Carbide Based Nano-Electro-Mechanical-System Micromachined Ultrasonic Transducers: Analytical Modeling and FEM Simulation

Reshmi Maity,N. P. Maity,K. Srinivasa Rao,Girija Sravani,K. Guha,S. Baishya 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.5

This paper models the fringing fi eld eff ects in a capacitive micromachined ultrasonic transducer (CMUT) structure for determining the sensitivity of the device. CMUT is used as a medical imaging component which can be an important module for sustainable healthcare system. The capacitance value of the device is evaluated based on Younes Ataiiyan’s method. To determine the equivalent capacitance of the device, the capacitances of the membrane, gap and silicon nitride insulating layer are associated in series. Mason’s modeling techniques are used to evaluate the membrane displacement. Circular membrane approximation model has been considered. Eff ects of the variation in membrane thickness, gap separation, and membrane radius on membrane displacement are investigated. The analytical prediction has been validated with the finite element method simulation results through PZFlex. Three dimensional modeling is carried out to accurately capture the characteristic behavior of the device. The agreements of both results are excellent which verifi es that fringing field effects exist in the device operation.

Rheological properties of graphene oxide liquid crystal

Kumar, P.,Maiti, U.N.,Lee, K.E.,Kim, S.O. Pergamon Press ; Elsevier Science Ltd 2014 Carbon Vol.80 No.-

We report the rheological properties of liquid crystalline graphene oxide (GO) aqueous dispersion. GO dispersions exhibit typical shear thinning behaviors of liquid crystals, which is described by power law or simple Curreau model. Irrespective of the shear rate, shear viscosity exhibits sudden decrease with the increase of GO composition around a critical volume fraction, φ<SUB>c</SUB>=0.33%, demonstrating typical colloidal isotropic-nematic phase transition. Dynamic measurements reveal the liquid-like (isotropic phase, G'>G'') behavior at a low GO composition (φ~0.08%) and solid-like (liquid crystalline) behavior at higher compositions (φ~0.45%), where G' exceeds over G''. Nematic gel-like phase is confirmed at a higher GO composition over φ>0.83%, where both G' and G'' moduli are nearly independent of frequency (ω). Simple power law scaling arguments are introduced to model the dependence of yield stress and viscoelastic moduli on the GO composition. We also observed the yield stress and rigidity percolation transition above phase transition composition φ<SUB>c</SUB>>0.33% with a percolation exponent of 1.3+/-0.1. These rheological insights provide valuable information for the liquid crystalline processing of GO based materials including fibers, sheets and other complex structures for electronic/optoelectronic and energy storage/conversion applications.

Performance Analysis of Nano-Electro-Mechanical-System Ultrasonic Sensor with Fringing Field Effects

Moumita Pal,N. P. Maity,S. Baishya,Reshmi Maity 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.6

In this work, modeling of the fringing field effects in a silicon carbide (SiC) based micromachined ultrasonic transducer (MUT) is reported. For such a micro/nano dimensional structure, the edge effect (fringing fi eld) extends far away and plays an important role in overall device operation. This extended field enhances the device equivalent capacitance. The analytically developed model is validated by finite element method (FEM). Electrostatic force developed and the actuated membrane displacement profiles are also evaluated in this work. The study involves Landau and Lifschitz method for evaluating equivalent device capacitance for establishing the fringing effect in the SiC MUT. Three dimensional modelling is also exhibited here to accurately portray the device characteristics precisely. Both the analytical and simulation establish the significant effect of fringing field in device operation.

Design of a Non-uniform Serpentine Asymmetric Cantilever RF-MEMS Shunt Capacitive Switch for RADAR Applications

Ch. Gopichand,Reshmi Maity,N. P. Maity,K. Srinivasa Rao,Koushik Guha,Santanu Maity,Ameen Eisnawi 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.4

This paper presents the design and simulation of Cantilever type RF-MEMS Capacitive shunt switch with meanders and perforations. The main objective of this paper is to reduce the pull-in voltage and increases isolation of the proposed switch. Electro-mechanics and Solid-mechanics are used to simulate the proposed switch by using COMSOL Multiphysics software. The capacitance, switching time, stress analysis are calculated and compare both theoretical and simulation results of the proposed switch. By varying diff erent beam thickness, materials, an air gap between the beam and signal line to calculate spring constant and pull-in voltage. The proposed switch having pull-in voltage is 1.371 V, the dielectric material Si 3 N 4 is to improve the capacitance analysis of the switch. The up and downstate capacitance is 7.073 fF, 1.259 pF. The RF performance is simulated by using Ansoft HFSS tool, the switch performs at low frequencies at 1–4 GHz range. The return (S 11 ) and insertion loss (S 12 ) of the proposed switch is − 30 dB, − 0.0516 dB and the switch having good isolation (S 21 ) is − 37.5 dB at 1.5 GHz frequency. The switch is suitable for radar and satellite communication applications.

Design and Analysis of Novel RF-MEMS Capacitive Type Shunt Switch for 5G Applications

Ch. Gopichand,Reshmi Maity,K. Srinivasa Rao,N. P. Maity,K. Girija Sravani 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.1

This paper presents the design and analysis of the RF-MEMS Capacitive type switch. Here, we have proposed different stages of shunt switches for better performance. The objective of the proposed work is to design different beam structures and to calculate pull-in voltage with various gaps, beam thickness, and materials in FEM tool. By decreasing the pull-in voltage we have taken perforations and diff erent meandering techniques (uniform and non-uniform). The material selection impacts the switch performance, here the dielectric material is taken as silicon nitride, the beam material is considered as gold, because of its high conducting material. The pull-in voltage of the proposed non-uniform meander type switch is 1.9 V, the RF-performance is measured in the HFSS and ADS equivalent circuit simulator tools, the return and insertion losses are obtained as −41.74 dB and -0.95 dB at 43 GHz, 40.10 GHz. The switch measured better isolation as – 36.25 dB, -20.55 dB at 20-40 GHz. The switch performance is obtained at 20-50 GHz range, therefore it can be feasible for 5G applications.

Analysis of Surface Potential and Electric Field for Fully Depleted Graded Channel Dual-Material-Double-Gate MOSFET through Modeling and Simulation

Himeli Chakrabarti,Reshmi Maity,Tijana Kevkić,Vladica Stojanović,N. P. Maity 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.4

This article is about an elaborative description of two dimensional investigative mathematical structure of fully depleted graded channel (GC) dual-material-double-gate (DMDG) silicon-on-insulator metal–oxide–semiconductor-fi eld-eff ecttransistor (SOI MOSFET). The surface potential contours in addition with electric field variation throughout the channel establish reduction of short-channel-effects (SCEs). To get better operational analysis, some new characteristics such as temperature effect and interface charge eff ects have been incorporated in the model. In this representation we also incorporate the consequences of high-k dielectric medium HfO2 instead of SiO2 and have made a comparison with the effect in various frameworks. In the GC DMDG composition, the surface potential as well as electric field throughout the channel shows close to step function variations which help to defeat the hot carrier along with drain-induced-barrier-lowering (DIBL) effects. As an outcome, the structure shows that the surface potential profi le increases by using GC DMDG structure over DMDG. All these outcomes of the proposed analytical representation have been compared by TCAD simulation consequence. Very good conformity is observed between them.

Design of RF-MEMS Switch Integration with Circular Microstrip Patch Antenna

K. Srinivasa Rao,Ch. Gopichand,Reshmi Maity,N. P. Maity,K. Girija Sravani 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.1

This paper presents the design and analysis of a microstrip circular patch antenna, integrated with the RF-MEMS capacitive type switch. Here, two diff erent types of RF-MEMS (Radio frequency Micro-electromechanical systems) switches are proposed, one is a bridge-type and the other is a single-beam type switch. These two switches are designed and simulated by using FEM (Finite Element Model) tool, the pull-in voltages of the two switches are obtained as 1.9 V, 4.9 V. Both switches are integrated with the circular patch antenna and measure the device characteristics and analysed in HFSS (High Frequency Structure Simulator) tool. The work is focused on analysing the performance of circular micro strip patch antenna such as return loss, radiation pattern, gain, VSWR (voltage standing wave ratio) and bandwidth and compared the performances of both switches are in ON and OFF condition. The circular microstrip patch antenna with RF-MEMS switches are designed to achieve antenna re-configurability at low frequencies up to 15 GHz.