SPICE simulation of surface acoustic wave interdigital transducers
01 Jul 1995-IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control (IEEE)-Vol. 42, Iss: 4, pp 784-786
TL;DR: In this paper, an electrical macromodel of Mason's equivalent circuit for an interdigital transducer (IDT) is proposed which is compatible to a widely used general purpose circuit simulator SPICE endowed with the capability to handle negative capacitances and inductances.
Abstract: Surface Acoustic Wave (SAW) devices, are not normally amenable to simulation through circuit simulators. In this letter, an electrical macromodel of Mason's Equivalent Circuit for an interdigital transducer (IDT) is proposed which is compatible to a widely used general purpose circuit simulator SPICE endowed with the capability to handle negative capacitances and inductances. Illustrations have been given to demonstrate the simplicity of ascertaining the frequency and time domain characteristics of IDT and amenability to simulate the IDT along with other external circuit elements. >
Citations
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TL;DR: The Mason crossed-field circuit model is generalized to simulate apodized interdigital transducers without channel division and this unichannel model is illustrated to successfully describe the frequency response of apodization inter digital transducers.
Abstract: The Mason crossed-field circuit model is generalized to simulate apodized interdigital transducers without channel division. The apodized transducer model is based on the transmission line model, and the artificial transformer with different voltage and current coupling ratios is used to independently obtain the transfer function and radiation admittance. In addition, a heuristic expression for transformer current ratios is used to approximate the radiation admittance of apodized transducers. Through comparing with the multichannel model, this unichannel model is illustrated to successfully describe the frequency response of apodized interdigital transducers.
19 citations
Cites background from "SPICE simulation of surface acousti..."
...Mason equivalent circuit by equivalent inductances and capacitances [ 10 ]....
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Dissertation•
19 Jan 2009
TL;DR: In this paper, a surface acoustic wave (SAW) pressure sensor using Aluminium Nitride (AlN) is presented, in which the wave velocity and coupling factor depend on the wave propagation medium.
Abstract: The goal of this thesis is the design of a surface acoustic wave (SAW) pressure sensor using Aluminium Nitride (AlN). Theoretical studies, realization, and characterization of the pressure sensor on different SAW structures are presented. The modeling of the sensor was performed using an equivalent circuit based on Mason model and Coupling-Of-Mode. The theoretical study, SAW parameters in different structures of AlN/SiO2/Si, AlN/Si, and AlN/Mo/Si are calculated and analyzed. From these analysis, the wave velocity as well as coupling factor could depend on the wave propagation medium. For each structure using AlN, we establish the range of thickness of AlN layer, in which there is a weak dependence of the wave velocity and coupling factor on the AlN layer thickness. The SAW devices should be designed, in particular for the choice of the thicknesses of the different layers, by taking into account the accuracy of the manufacturing process, to reduce dispersion effects on the sensors characteristics. Besides, we also performed the mechanical analysis of the membrane under pressure and we have deduced the pressure sensitivity. The effect of frequency variation due to temperature change in SAW device using AlN is given. For pressure measurement applications, we propose a method to reduce temperature change effects. Concerning the fabrication process, we propose to use surface micro-machining. This kind of fabrication process allows to obtain exactly the dimensions of membranes used in pressure sensors and it also allows to have any kind of geometry due to the silicon etch stop wall. Characterizations of AlN film are done during fabrication process. We found that to increase the piezoelectric behavior of AlN, there are three possible ways: using a bottom Mo layer, decreasing the roughness of the layer below the AlN layer up to 0.2nm and increasing the thickness of AlN. Acoustic propagation losses, coupling factor, effect of Mo layer and the effect of thin polyimide film on the center frequency are experimentally analyzed. Finally, the measured pressure sensitivity of our device is presented. This last result is promising.
12 citations
TL;DR: It is shown that functionally graded piezoelectric materials can be used to make modal actuators through theoretical analyses of the excitation of extensional motion in an elastic rod and Rayleigh surface waves over an elastic half-plane.
Abstract: We show that functionally graded piezoelectric materials can be used to make modal actuators through theoretical analyses of the excitation of extensional motion in an elastic rod and Rayleigh surface waves over an elastic half-plane. The results suggest alternatives with certain advantages for the excitation of bulk and surface acoustic waves.
10 citations
TL;DR: A surface acoustic wave (SAW) interdigital transducer (IDT) has been modeled as a resistance-inductance-capacitance (RLC) network, which includes the effects of metal shorting and energy storage at metal discontinuities, as well as an arbitrary polarity sequence of fingers.
Abstract: In the present work, a surface acoustic wave (SAW) interdigital transducer (IDT) has been modeled as a resistance-inductance-capacitance (RLC) network. The model includes the effects of metal shorting and energy storage at metal discontinuities, as well as an arbitrary polarity sequence of fingers. A C++ program generates the equivalent electrical circuit, which is directly simulated by Simulation Program with Integrated Circuit Emphasis (SPICE), a popular electrical circuit simulator. Simulations compare well with reported experimental results, validating the proposed model.
10 citations
Cites background or methods from "SPICE simulation of surface acousti..."
...For the determination of a reactive network, corresponding to the given functional characteristics, Foster’s theorem is used [ 2 ]....
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...The present work is based on the approach using mixed circuit model of the MEC [ 2 ]....
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...In the direction of overcoming this limitation, some work was reported on circuit simulation of SAW devices [ 2 ]....
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01 Jan 2007
TL;DR: In this article, a burst transceiver is used to send a burst signal to the SAW sensor and processes the sensor response, and a miniaturized version is designed and fabricated on a PCB.
Abstract: Due to their small size and ruggedness, Surface Acoustic Wave (SAW) devices have been widely used as part of wireless sensing or identification system especially in inaccessible and inhospitable environments. In addition, SAW devices find widespread applications as filters in communication systems and also as physical, chemical and bio-sensors and ID tags. The passive wireless SAW sensing system mainly consists of a passive SAW sensor and an interrogation unit which sends a burst signal to the SAW sensor and processes the sensor response. Theobjectives of this work were designing, prototyping and fabricating the interrogation unit on a PCB and also designing modeling, simulating and fabricating SAW devices. Significant results obtained from the burst transceiver and simulation as well as measurement results of SAW devices will be presented together with some of the challenges faced. The interrogation unit is a burst transceiver operating in the Industrial, Scientific and Medical (ISM) band at 433 MEIz. The prototype was built using connectorized modules and manufacturer demonstration boards. Once the prototype burst transceiver was tested for its functionality, a miniaturized version was designed and fabricated on a PCB. The PCB layout was prepared using FreePCB™ software and manufactured at Cirexx International, CA. Both the prototype and the PCB burst transceiver is characterized using a cascaded gain and noise figure analysis performed for both the transmit and the receive sections. SAW delay lines and resonators operating at 100 MHz were first designed and then fabricated at the University of Michigan’s Micro/Nano fabrication facility in Ann Arbor, MI. Simulation of the frequency response of SAW devices were performed in MATLAB™, PSpice Capture™ and CoventorWare™. The design aspects of SAW devices and details of modeling the SAW devices in each of the above software packages are presented. Simulation results obtained from all the three software packages are compared with measured responses and the relative merits and demerits of each method will be presented.
9 citations
References
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Book•
01 Jan 1942
809 citations
"SPICE simulation of surface acousti..." refers methods in this paper
...An attempt has also been made to make the well known Mason’s Equivalent Circuit (MEC) [4], [5], compatible to SPICE simulation [6], where the effort has been directed toward circumventing the problems associated with negative capacitance inherent in the MEC....
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...We propose below a macromodel for the SAW Interdigital Transducer (IDT), derived from the MEC, which is amenable to SPICE simulation without the need to avoid the negative capacitance....
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...3, is meant to represent any resistance(s) external to the MEC, e.g., electrode/finger resistance....
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...The approach is based on the behavioral approximation of specific elements of the MEC by equivalent inductance and capacitance combinations....
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...Specifically, the elements jRo tan ( =2) and jRo cosec in the MEC can be behaviorally approximated by networks, shown in Fig....
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TL;DR: In this paper, an acoustic surface wave transducers of the interdigital electrode form are used to represent the transducer as a chain of identical three-ports which are acoustically in cascade but electrically in parallel.
Abstract: Immittance, transfer, and scattering characteristics are studied for acoustic surface wave transducers of the interdigital electrode form. Linear network models are used to represent the transducer as a chain of identical three-ports which are acoustically in cascade but electrically in parallel. Transducer operation at acoustic synchronism is described theoretically and compared to current experimental data for transducers operating at 100 MHz and fabricated on lithium niobate. Favorable lithium niobate configurations for efficient, broad-band transducer operation are given. Scattering characteristics as a function of electric load are discussed. Low values of acoustic reflection loss are predicted theoretically and observed experimentally when the electric load and transducer capacitance are in resonance. The frequency dependence of transducer radiation immittance is studied, and the response is found to be analogous to the response of an endfire antenna array.
649 citations
"SPICE simulation of surface acousti..." refers methods in this paper
...[5], it has since been revised and modified extensively for SAW IDT’s [7]....
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...An attempt has also been made to make the well known Mason’s Equivalent Circuit (MEC) [4], [5], compatible to SPICE simulation [6], where the effort has been directed toward circumventing the problems associated with negative capacitance inherent in the MEC....
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...The inherent problem in the MEC of a singularity at synchronous frequencies [5] which manifests in simulations also, can be surmounted, as in HSPICE, by the use of double sweep in AC analysis....
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TL;DR: In this paper, transmission line analogous circuits for piezoelectric transducers are developed which employ controlled sources rather than the traditional transformer to model the coupling between the electrical and the mechanical systems.
Abstract: Transmission line analogous circuits for piezoelectric transducers are developed which employ controlled sources rather than the traditional transformer to model the coupling between the electrical and the mechanical systems. A novel method is used to derive each model that consists of adding a term that is equal to zero to one of the device electromechanical equations. When this is done, it is shown that the equations can be cast into the form of the familiar telegraphist's equations for the voltage and current on an electrical transmission line. The circuits are derived for both the thickness-mode piezoelectric transducer and the side-electrode bar piezoelectric transducer. SPICE models of the analogous circuits are presented and an example simulation is given. >
157 citations
"SPICE simulation of surface acousti..." refers methods in this paper
...Some work has been reported on rendering the piezoelectric bulk acoustic wave (BAW) transducer compatible to computer-aided circuit simulation by SPICE (Simulation Program with Integrated Circuit Emphasis) [1], either through replacement of the elementary piezoelectric transducers in the form of artificial transmission line [2], or by the introduction of controlled-source analogous circuit models [3]....
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TL;DR: Application a la conception de transducteurs d'ultrasons, determination de leurs caracteristiques et application de leur application d'approximation de l'inevitableité.
Abstract: Application a la conception de transducteurs d'ultrasons. Determination de leurs caracteristiques
107 citations
"SPICE simulation of surface acousti..." refers methods in this paper
...An attempt has also been made to make the well known Mason’s Equivalent Circuit (MEC) [4], [5], compatible to SPICE simulation [6], where the effort has been directed toward circumventing the problems associated with negative capacitance inherent in the MEC....
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