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Papers by Ashish Kumar Namdeo

Research paper thumbnail of Optimised Algorithm for Step Count Estimation Using Sensor Data from Smartphones and Wearables

2022 IEEE Region 10 Symposium (TENSYMP)

Research paper thumbnail of Surface Acoustic Wave Devices with Non-Contact Interdigital Transducers Ashish

Research paper thumbnail of Extraction of Electrical Equivalent Circuit of One Port SAW Resonator Using FEM-based Simulation

The paper presents a method of extraction of electrical equivalent circuit of a one port surface ... more The paper presents a method of extraction of electrical equivalent circuit of a one port surface acoustic wave (SAW) resonator from the results of simulation based on finite element method using COMSOL Multiphysics software. A one port SAW resonator consists of large number of periodic interdigital transducer (IDT) electrodes fabricated on the surface of a piezoelectric substrate. A section of aluminum IDT structure patterned on YZ lithium niobate piezoelectric substrate with periodic boundary condition is incorporated in the simulation. The equivalent circuit of a SAW resonator consists of motional resistance, capacitance and inductance connected in series, and static capacitance in parallel. The electrical resonance characteristics of SAW resonator obtained from frequency domain analysis provided by COMSOL Multiphysics are used to calculate the equivalent circuit parameters. The calculation of electrical equivalent circuit parameters is useful in designing matching circuits for SA...

Research paper thumbnail of ScienceDirect International Conference On DESIGN AND MANUFACTURING , IConDM 2013 Simulation on Effects of Electrical Loading due to Interdigital Transducers in Surface Acoustic Wave Resonator

This paper investigates the effects of electrical loading due to metallic interdigital transducer... more This paper investigates the effects of electrical loading due to metallic interdigital transducer (IDT) on surface acoustic wave (SAW) velocity in SAW resonators by simulation using FEM in COMSOL Multiphysics. The IDT electrodes fabricated over the piezo-substrate short circuit the parallel electric field associated with SAW under the IDT during wave propagation and affect the SAW phase velocity. The simulation considers a SAW resonator with massless infinite number of IDT fingers on Y Z cut lithium niobate substrate. The changes in resonance frequency and SAW phase velocity of SAW resonator due to electrical loading are studied for various metallization ratios. The electric field distribution at the surface of piezo-substrate is obtained and it is observed that the short circuit of the electric field due to metallic IDT reduces the SAW phase velocity; consequently, the resonance frequency of the SAW device decreases. © 2013 The Authors. Published by Elsevier Ltd. Selection and peer...

Research paper thumbnail of FEM simulation of generation of bulk acoustic waves and their effects in SAW devices

This paper presents finite element method (FEM) simulation study of the generation of bulk acoust... more This paper presents finite element method (FEM) simulation study of the generation of bulk acoustic waves (BAWs) and their effect on the performance of surface acoustic wave (SAW) devices, using COMSOL Multiphysics™. A SAW delay line structure using YZ-cut lithium niobate substrate is simulated. The radiation of the bulk waves in all angles into the interior of the substrate is analyzed. The bulk acoustic waves in SAW devices can affect the device response. Since BAW reflects from the bottom surface of the substrate and interferes with the received SAW at the output, bulk radiation needs careful consideration in the design of SAW devices.

Research paper thumbnail of Extraction of COM Parameters and Quality Factor of One Port SAW Resonator using FEM Based Simulation

We present a method of extraction of coupling of modes (COM) parameters and quality factor for a ... more We present a method of extraction of coupling of modes (COM) parameters and quality factor for a one port surface acoustic wave (SAW) resonator from the results of finite element analysis in COMSOL Multiphysics. The parameters are calculated for various aspect ratios of the interdigital transducer (IDT) electrodes. It is needed to reduce resistive loss at high frequency due to reduced size of IDT electrodes. The calculation of COM parameters and quality factor for various aspect ratios of IDT electrodes is useful in designing high frequency SAW devices.

Research paper thumbnail of FEM Study on Contactless Excitation of Acoustic Waves in SAW Devices

In this paper a finite element method (FEM) study of a surface acoustic wave (SAW) device excited... more In this paper a finite element method (FEM) study of a surface acoustic wave (SAW) device excited by electrostatic coupling method is performed by using COMSOL Multiphysics. We have modeled a Rayleigh wave type SAW device by choosing YZ Lithium niobate as the substrate. The effect of external radio frequency (RF) field to the SAW device is analyzed. The effect of distance between the contactless electrodes and the SAW device is simulated and the amplitude of the propagating SAW is analyzed. An IDT structure to realize the electrostatic coupling of signals by using the contactless electrodes is discussed.

Research paper thumbnail of Simplified Model for FEM Simulation of SAW Delay Line Sensor

Surface acoustic wave (SAW) devices can be modeled using various methods such as equivalent circu... more Surface acoustic wave (SAW) devices can be modeled using various methods such as equivalent circuit model, coupling of modes method and finite element method (FEM). FEM simulation of SAW devices serves to optimize SAW structures and allows getting insight physics of propagation of SAW over the substrate. In most of the earlier work on FEM simulation of SAW sensors, entire device structure is considered for the simulation and the number of degrees of freedom (DOF) to solve is significantly high. Thus it is important to identify valid approximation and simplified models to reduce the computational cost. In this paper a 2D-finite FEM simulation of SAW delay line model using COMSOL Multiphysics (commercial FEM software) is discussed. We have modeled a Rayleigh wave type SAW device choosing YZ Lithium Niobate as the substrate. The major contribution of this work is the application of periodic boundaries to the transmitter interdigital transducer (IDT) to reduce the number of degrees of f...

Research paper thumbnail of Extraction of COM Parameters and Quality Factor of One Port SAW Resonator using FEM Based Simulation

The paper presents a method of extraction of coupling of modes (COM) parameters for a one port su... more The paper presents a method of extraction of coupling of modes (COM) parameters for a one port surface acoustic wave (SAW) resonator from the results of finite element analysis in COMSOL Multiphysics®. The COM parameters calculated are electromechanical coupling coefficient, reflection coefficient, and SAW phase velocity. In addition, the quality factor of the SAW resonator is determined. The parameters are calculated for various aspect ratios of the interdigital transducer (IDT) electrodes. An IDT is a metallic periodic comb-shaped structure fabricated on the surface of a piezoelectric substrate. A section of IDT structure patterned on YZ lithium niobate substrate with periodic boundary condition is incorporated in the simulation. The result of Eigen mode analysis provided by COMSOL Multiphysics® is used to calculate the COM parameters. The calculation of COM parameters and quality factor for various aspect ratios of IDT electrodes is useful in designing high frequency SAW devices.

Research paper thumbnail of FEM Study on Contactless Excitation of Acoustic Waves in SAW Devices

Proceedings of the …, 2009

In this paper a finite element method (FEM) study of a surface acoustic wave (SAW) device excited... more In this paper a finite element method (FEM) study of a surface acoustic wave (SAW) device excited by electrostatic coupling method is performed by using COMSOL Multiphysics. We have modeled a Rayleigh wave type SAW device by choosing YZ Lithium niobate as the substrate. The effect of external radio frequency (RF) field to the SAW device is analyzed. The effect of distance between the contactless electrodes and the SAW device is simulated and the amplitude of the propagating SAW is analyzed. An IDT structure to realize the electrostatic coupling of signals by using the contactless electrodes is discussed.

Research paper thumbnail of Extraction of COM Parameters and Quality Factor of One Port SAW Resonator using FEM Based Simulation

We present a method of extraction of coupling of modes (COM) parameters and quality factor for a ... more We present a method of extraction of coupling of modes (COM) parameters and quality factor for a one port surface acoustic wave (SAW) resonator from the results of finite element analysis in COMSOL Multiphysics. The parameters are calculated for various aspect ratios of the interdigital transducer (IDT) electrodes. It is needed to reduce resistive loss at high frequency due to reduced size of IDT electrodes. The calculation of COM parameters and quality factor for various aspect ratios of IDT electrodes is useful in designing high frequency SAW devices.

Research paper thumbnail of FEM Study on the Effect of Metallic Interdigital Transducers on Surface Acoustic Wave (SAW) Velocity in SAW Devices

In this paper, we present study on the mass loading effect of the interdigital transducer (IDT) o... more In this paper, we present study on the mass loading effect of the interdigital transducer (IDT) on surface acoustic wave (SAW) velocity in SAW devices, using COMSOL Multiphysics™. An IDT consists of metallic comb-shaped electrodes normally fabricated over the surface of the piezoelectric substrate. Owing to the mass load of metallic IDTs over substrate the surface wave's velocity reduces. We have simulated a one port SAW resonator represents the mass loaded device made on YZ-cut lithium niobate substrate and investigated the reduction of SAW velocity caused by the mass loading of metal IDT. An Eigen frequency analysis provided by COMSOL Multiphysics™ is useful for finding the true surface and bulk wave velocities in the absence of IDT. The surface wave velocity and the bulk wave velocity are observed. The surface plots of surface and bulk standing waves in the device with IDT and without IDT are shown.

Research paper thumbnail of Simulation on Effects of Electrical Loading due to Interdigital Transducers in Surface Acoustic Wave Resonator

Procedia Engineering, 2013

This paper investigates the effects of electrical loading due to metallic interdigital transducer... more This paper investigates the effects of electrical loading due to metallic interdigital transducer (IDT) on surface acoustic wave (SAW) velocity in SAW resonators by simulation using FEM in COMSOL Multiphysics. The IDT electrodes fabricated over the piezo-substrate short circuit the parallel electric field associated with SAW under the IDT during wave propagation and affect the SAW phase velocity. The simulation considers a SAW resonator with massless infinite number of IDT fingers on Y Z cut lithium niobate substrate. The changes in resonance frequency and SAW phase velocity of SAW resonator due to electrical loading are studied for various metallization ratios. The electric field distribution at the surface of piezo-substrate is obtained and it is observed that the short circuit of the electric field due to metallic IDT reduces the SAW phase velocity; consequently, the resonance frequency of the SAW device decreases.

Research paper thumbnail of Simplified Model for FEM Simulation of SAW Delay Line Sensor

Procedia Engineering, 2012

Surface acoustic wave (SAW) devices can be modeled using various methods such as equivalent circu... more Surface acoustic wave (SAW) devices can be modeled using various methods such as equivalent circuit model, coupling of modes method and finite element method (FEM). FEM simulation of SAW devices serves to optimize SAW structures and allows getting insight physics of propagation of SAW over the substrate. In most of the earlier work on FEM simulation of SAW sensors, entire device structure is considered for the simulation and the number of degrees of freedom (DOF) to solve is significantly high. Thus it is important to identify valid approximation and simplified models to reduce the computational cost. In this paper a 2D-finite FEM simulation of SAW delay line model using COMSOL Multiphysics (commercial FEM software) is discussed. We have modeled a Rayleigh wave type SAW device choosing YZ Lithium Niobate as the substrate. The major contribution of this work is the application of periodic boundaries to the transmitter interdigital transducer (IDT) to reduce the number of degrees of freedom of a SAW delay line model solution. The simulation methodology and time domain response of the model are discussed.

Research paper thumbnail of FEM Simulation of Generation of Bulk Acoustic Waves and Their Effects in SAW Devices

cds.comsol.com

This paper presents finite element method (FEM) simulation study of the generation of bulk acoust... more This paper presents finite element method (FEM) simulation study of the generation of bulk acoustic waves (BAWs) and their effect on the performance of surface acoustic wave (SAW) devices, using COMSOL Multiphysics™. A SAW delay line structure using YZ-cut lithium niobate substrate is simulated. The radiation of the bulk waves in all angles into the interior of the substrate is analyzed. The bulk acoustic waves in SAW devices can affect the device response. Since BAW reflects from the bottom surface of the substrate and interferes with the received SAW at the output, bulk radiation needs careful consideration in the design of SAW devices.

Research paper thumbnail of FEM Study on Contactless Excitation of Acoustic Waves in SAW Devices

cds.comsol.com

In this paper a finite element method (FEM) study of a surface acoustic wave (SAW) device excited... more In this paper a finite element method (FEM) study of a surface acoustic wave (SAW) device excited by electrostatic coupling method is performed by using COMSOL Multiphysics. We have modeled a Rayleigh wave type SAW device by choosing YZ Lithium niobate as the substrate. The effect of external radio frequency (RF) field to the SAW device is analyzed. The effect of distance between the contactless electrodes and the SAW device is simulated and the amplitude of the propagating SAW is analyzed. An IDT structure to realize the electrostatic coupling of signals by using the contactless electrodes is discussed.

Research paper thumbnail of Optimised Algorithm for Step Count Estimation Using Sensor Data from Smartphones and Wearables

2022 IEEE Region 10 Symposium (TENSYMP)

Research paper thumbnail of Surface Acoustic Wave Devices with Non-Contact Interdigital Transducers Ashish

Research paper thumbnail of Extraction of Electrical Equivalent Circuit of One Port SAW Resonator Using FEM-based Simulation

The paper presents a method of extraction of electrical equivalent circuit of a one port surface ... more The paper presents a method of extraction of electrical equivalent circuit of a one port surface acoustic wave (SAW) resonator from the results of simulation based on finite element method using COMSOL Multiphysics software. A one port SAW resonator consists of large number of periodic interdigital transducer (IDT) electrodes fabricated on the surface of a piezoelectric substrate. A section of aluminum IDT structure patterned on YZ lithium niobate piezoelectric substrate with periodic boundary condition is incorporated in the simulation. The equivalent circuit of a SAW resonator consists of motional resistance, capacitance and inductance connected in series, and static capacitance in parallel. The electrical resonance characteristics of SAW resonator obtained from frequency domain analysis provided by COMSOL Multiphysics are used to calculate the equivalent circuit parameters. The calculation of electrical equivalent circuit parameters is useful in designing matching circuits for SA...

Research paper thumbnail of ScienceDirect International Conference On DESIGN AND MANUFACTURING , IConDM 2013 Simulation on Effects of Electrical Loading due to Interdigital Transducers in Surface Acoustic Wave Resonator

This paper investigates the effects of electrical loading due to metallic interdigital transducer... more This paper investigates the effects of electrical loading due to metallic interdigital transducer (IDT) on surface acoustic wave (SAW) velocity in SAW resonators by simulation using FEM in COMSOL Multiphysics. The IDT electrodes fabricated over the piezo-substrate short circuit the parallel electric field associated with SAW under the IDT during wave propagation and affect the SAW phase velocity. The simulation considers a SAW resonator with massless infinite number of IDT fingers on Y Z cut lithium niobate substrate. The changes in resonance frequency and SAW phase velocity of SAW resonator due to electrical loading are studied for various metallization ratios. The electric field distribution at the surface of piezo-substrate is obtained and it is observed that the short circuit of the electric field due to metallic IDT reduces the SAW phase velocity; consequently, the resonance frequency of the SAW device decreases. © 2013 The Authors. Published by Elsevier Ltd. Selection and peer...

Research paper thumbnail of FEM simulation of generation of bulk acoustic waves and their effects in SAW devices

This paper presents finite element method (FEM) simulation study of the generation of bulk acoust... more This paper presents finite element method (FEM) simulation study of the generation of bulk acoustic waves (BAWs) and their effect on the performance of surface acoustic wave (SAW) devices, using COMSOL Multiphysics™. A SAW delay line structure using YZ-cut lithium niobate substrate is simulated. The radiation of the bulk waves in all angles into the interior of the substrate is analyzed. The bulk acoustic waves in SAW devices can affect the device response. Since BAW reflects from the bottom surface of the substrate and interferes with the received SAW at the output, bulk radiation needs careful consideration in the design of SAW devices.

Research paper thumbnail of Extraction of COM Parameters and Quality Factor of One Port SAW Resonator using FEM Based Simulation

We present a method of extraction of coupling of modes (COM) parameters and quality factor for a ... more We present a method of extraction of coupling of modes (COM) parameters and quality factor for a one port surface acoustic wave (SAW) resonator from the results of finite element analysis in COMSOL Multiphysics. The parameters are calculated for various aspect ratios of the interdigital transducer (IDT) electrodes. It is needed to reduce resistive loss at high frequency due to reduced size of IDT electrodes. The calculation of COM parameters and quality factor for various aspect ratios of IDT electrodes is useful in designing high frequency SAW devices.

Research paper thumbnail of FEM Study on Contactless Excitation of Acoustic Waves in SAW Devices

In this paper a finite element method (FEM) study of a surface acoustic wave (SAW) device excited... more In this paper a finite element method (FEM) study of a surface acoustic wave (SAW) device excited by electrostatic coupling method is performed by using COMSOL Multiphysics. We have modeled a Rayleigh wave type SAW device by choosing YZ Lithium niobate as the substrate. The effect of external radio frequency (RF) field to the SAW device is analyzed. The effect of distance between the contactless electrodes and the SAW device is simulated and the amplitude of the propagating SAW is analyzed. An IDT structure to realize the electrostatic coupling of signals by using the contactless electrodes is discussed.

Research paper thumbnail of Simplified Model for FEM Simulation of SAW Delay Line Sensor

Surface acoustic wave (SAW) devices can be modeled using various methods such as equivalent circu... more Surface acoustic wave (SAW) devices can be modeled using various methods such as equivalent circuit model, coupling of modes method and finite element method (FEM). FEM simulation of SAW devices serves to optimize SAW structures and allows getting insight physics of propagation of SAW over the substrate. In most of the earlier work on FEM simulation of SAW sensors, entire device structure is considered for the simulation and the number of degrees of freedom (DOF) to solve is significantly high. Thus it is important to identify valid approximation and simplified models to reduce the computational cost. In this paper a 2D-finite FEM simulation of SAW delay line model using COMSOL Multiphysics (commercial FEM software) is discussed. We have modeled a Rayleigh wave type SAW device choosing YZ Lithium Niobate as the substrate. The major contribution of this work is the application of periodic boundaries to the transmitter interdigital transducer (IDT) to reduce the number of degrees of f...

Research paper thumbnail of Extraction of COM Parameters and Quality Factor of One Port SAW Resonator using FEM Based Simulation

The paper presents a method of extraction of coupling of modes (COM) parameters for a one port su... more The paper presents a method of extraction of coupling of modes (COM) parameters for a one port surface acoustic wave (SAW) resonator from the results of finite element analysis in COMSOL Multiphysics®. The COM parameters calculated are electromechanical coupling coefficient, reflection coefficient, and SAW phase velocity. In addition, the quality factor of the SAW resonator is determined. The parameters are calculated for various aspect ratios of the interdigital transducer (IDT) electrodes. An IDT is a metallic periodic comb-shaped structure fabricated on the surface of a piezoelectric substrate. A section of IDT structure patterned on YZ lithium niobate substrate with periodic boundary condition is incorporated in the simulation. The result of Eigen mode analysis provided by COMSOL Multiphysics® is used to calculate the COM parameters. The calculation of COM parameters and quality factor for various aspect ratios of IDT electrodes is useful in designing high frequency SAW devices.

Research paper thumbnail of FEM Study on Contactless Excitation of Acoustic Waves in SAW Devices

Proceedings of the …, 2009

In this paper a finite element method (FEM) study of a surface acoustic wave (SAW) device excited... more In this paper a finite element method (FEM) study of a surface acoustic wave (SAW) device excited by electrostatic coupling method is performed by using COMSOL Multiphysics. We have modeled a Rayleigh wave type SAW device by choosing YZ Lithium niobate as the substrate. The effect of external radio frequency (RF) field to the SAW device is analyzed. The effect of distance between the contactless electrodes and the SAW device is simulated and the amplitude of the propagating SAW is analyzed. An IDT structure to realize the electrostatic coupling of signals by using the contactless electrodes is discussed.

Research paper thumbnail of Extraction of COM Parameters and Quality Factor of One Port SAW Resonator using FEM Based Simulation

We present a method of extraction of coupling of modes (COM) parameters and quality factor for a ... more We present a method of extraction of coupling of modes (COM) parameters and quality factor for a one port surface acoustic wave (SAW) resonator from the results of finite element analysis in COMSOL Multiphysics. The parameters are calculated for various aspect ratios of the interdigital transducer (IDT) electrodes. It is needed to reduce resistive loss at high frequency due to reduced size of IDT electrodes. The calculation of COM parameters and quality factor for various aspect ratios of IDT electrodes is useful in designing high frequency SAW devices.

Research paper thumbnail of FEM Study on the Effect of Metallic Interdigital Transducers on Surface Acoustic Wave (SAW) Velocity in SAW Devices

In this paper, we present study on the mass loading effect of the interdigital transducer (IDT) o... more In this paper, we present study on the mass loading effect of the interdigital transducer (IDT) on surface acoustic wave (SAW) velocity in SAW devices, using COMSOL Multiphysics™. An IDT consists of metallic comb-shaped electrodes normally fabricated over the surface of the piezoelectric substrate. Owing to the mass load of metallic IDTs over substrate the surface wave's velocity reduces. We have simulated a one port SAW resonator represents the mass loaded device made on YZ-cut lithium niobate substrate and investigated the reduction of SAW velocity caused by the mass loading of metal IDT. An Eigen frequency analysis provided by COMSOL Multiphysics™ is useful for finding the true surface and bulk wave velocities in the absence of IDT. The surface wave velocity and the bulk wave velocity are observed. The surface plots of surface and bulk standing waves in the device with IDT and without IDT are shown.

Research paper thumbnail of Simulation on Effects of Electrical Loading due to Interdigital Transducers in Surface Acoustic Wave Resonator

Procedia Engineering, 2013

This paper investigates the effects of electrical loading due to metallic interdigital transducer... more This paper investigates the effects of electrical loading due to metallic interdigital transducer (IDT) on surface acoustic wave (SAW) velocity in SAW resonators by simulation using FEM in COMSOL Multiphysics. The IDT electrodes fabricated over the piezo-substrate short circuit the parallel electric field associated with SAW under the IDT during wave propagation and affect the SAW phase velocity. The simulation considers a SAW resonator with massless infinite number of IDT fingers on Y Z cut lithium niobate substrate. The changes in resonance frequency and SAW phase velocity of SAW resonator due to electrical loading are studied for various metallization ratios. The electric field distribution at the surface of piezo-substrate is obtained and it is observed that the short circuit of the electric field due to metallic IDT reduces the SAW phase velocity; consequently, the resonance frequency of the SAW device decreases.

Research paper thumbnail of Simplified Model for FEM Simulation of SAW Delay Line Sensor

Procedia Engineering, 2012

Surface acoustic wave (SAW) devices can be modeled using various methods such as equivalent circu... more Surface acoustic wave (SAW) devices can be modeled using various methods such as equivalent circuit model, coupling of modes method and finite element method (FEM). FEM simulation of SAW devices serves to optimize SAW structures and allows getting insight physics of propagation of SAW over the substrate. In most of the earlier work on FEM simulation of SAW sensors, entire device structure is considered for the simulation and the number of degrees of freedom (DOF) to solve is significantly high. Thus it is important to identify valid approximation and simplified models to reduce the computational cost. In this paper a 2D-finite FEM simulation of SAW delay line model using COMSOL Multiphysics (commercial FEM software) is discussed. We have modeled a Rayleigh wave type SAW device choosing YZ Lithium Niobate as the substrate. The major contribution of this work is the application of periodic boundaries to the transmitter interdigital transducer (IDT) to reduce the number of degrees of freedom of a SAW delay line model solution. The simulation methodology and time domain response of the model are discussed.

Research paper thumbnail of FEM Simulation of Generation of Bulk Acoustic Waves and Their Effects in SAW Devices

cds.comsol.com

This paper presents finite element method (FEM) simulation study of the generation of bulk acoust... more This paper presents finite element method (FEM) simulation study of the generation of bulk acoustic waves (BAWs) and their effect on the performance of surface acoustic wave (SAW) devices, using COMSOL Multiphysics™. A SAW delay line structure using YZ-cut lithium niobate substrate is simulated. The radiation of the bulk waves in all angles into the interior of the substrate is analyzed. The bulk acoustic waves in SAW devices can affect the device response. Since BAW reflects from the bottom surface of the substrate and interferes with the received SAW at the output, bulk radiation needs careful consideration in the design of SAW devices.

Research paper thumbnail of FEM Study on Contactless Excitation of Acoustic Waves in SAW Devices

cds.comsol.com

In this paper a finite element method (FEM) study of a surface acoustic wave (SAW) device excited... more In this paper a finite element method (FEM) study of a surface acoustic wave (SAW) device excited by electrostatic coupling method is performed by using COMSOL Multiphysics. We have modeled a Rayleigh wave type SAW device by choosing YZ Lithium niobate as the substrate. The effect of external radio frequency (RF) field to the SAW device is analyzed. The effect of distance between the contactless electrodes and the SAW device is simulated and the amplitude of the propagating SAW is analyzed. An IDT structure to realize the electrostatic coupling of signals by using the contactless electrodes is discussed.