Plate Wave Resonators Research Articles

3.2 GHz first shear horizontal-mode plate wave resonator on a 175°YX LiNbO3 thin plate showing 24.6% bandwidth

In this study, a first shear horizontal (SH1) mode plate wave resonator for HF and wide-band filters was investigated. From FEM simulation, the SH1 mode plate wave exhibited a high phase velocity of 23 km s−1 and a high electro-mechanical coupling factor (k 2) of 37% on (0°, 85°, 0°) LiNbO3 (LN) with a thickness of 0.1λ (λ: wavelength). The SH1 mode resonator was fabricated on a 0.5–0.57 μm thick LN film. An 80 nm Al IDT electrode was formed with λ varied from 4–16 μm. Finally, 50 nm thick Al was deposited to form an electrically short bottom plane, which was required to generate a SH1 mode wave. The fabricated device exhibited a resonance frequency (f r) of 2.24 GHz, an anti-resonance frequency (f a) of 2.8 GHz, a wide fractional bandwidth (FBW) of 20%, an impedance (Z) ratio of 35.4 dB, and TCF of −90.8 ppm/°C at f r and −74.8 ppm/°C at f a.

Ultra-wideband T- and π-type ladder filters using a fundamental shear horizontal mode plate wave in a LiNbO3 plate

A fundamental shear horizontal mode (SH0) plate wave in a thin (0°, 115°–120°, 0°) LiNbO3 plate has electromechanical coupling factor k2 larger than 50%. In this study, ultra-wideband π-type and T-type ladder filters composed of three SH0 plate wave resonators were fabricated and characterized. The interdigital transducer (IDT) pitch (P) ratio of IDTs in the parallel and series arm resonators (PR: IDT pitch of parallel arm resonator (Pparallel)/that of series arm resonator (Pseries)) was experimentally investigated. The 3 dB bandwidth is as large as 33%–61%, depending on the IDT pitch ratio. The insertion loss and shape factor in terms of the IDT pitch ratio are also reported.

Wideband acoustic wave resonators composed of hetero acoustic layer structure

“Hetero acoustic layer (HAL) surface acoustic wave (SAW) device” is a new type of SAW device using a single crystal piezoelectric thin plate supported by a substrate. In this study, a HAL SAW resonator using a LiNbO3 (LN) thin plate and a multi-layer acoustic film was designed by finite element method (FEM) and fabricated. The thickness of LN is 3.6 µm and the pitch of an interdigital transducer (IDT) (λ) is 5.24 µm for a resonance frequency of 600 MHz. The multi-layer acoustic film is composed of 3 layers of SiO2 and AlN for each, i.e., 6 layers in total, alternately deposited on a glass substrate. The HAL SAW resonator achieved a wide bandwidth of 20.3% and a high impedance ratio of 83 dB. Compared with a 0th shear horizontal (SH0) mode plate wave resonator, the performance is better and the thickness of LN is 7 times larger. The HAL SAW without a cavity is advantageous in terms of mechanical stability, thickness controllability and fabrication yield.

Tunable rejection filters with ultra-wideband using zeroth shear mode plate wave resonators

This paper reports wide band rejection filters and tunable rejection filters using ultra-wideband zeroth shear mode (SH0) plate wave resonators. The frequency range covers the digital TV band in Japan that runs from 470 to 710 MHz. This range has been chosen to meet the TV white space cognitive radio requirements of rejection filters. Wide rejection bands were obtained using several resonators with different frequencies. Tunable rejection filters were demonstrated using Si diodes connected to the band rejection filters. Wide tunable ranges as high as 31% were measured by applying a DC voltage to the Si diodes.

Simulation of solidly mounted plate wave resonator with wide bandwidth using 0-th shear horizontal mode in LiNbO3 plate

A cognitive radio system using a vacant frequency band of digital TV channels (TV white space) requires a tunable filter with wide tunable ranges of center frequency and bandwidth. An ultra-wideband resonator is a key device to implement the tunable filter, because the tunable range is limited by the bandwidth (BW) of the resonators. A 0-th shear horizontal (SH0) mode plate wave resonator using an ultra-thin LiNbO3 plate is known to have a large electromechanical coupling factor, i.e., a large BW, but the structural fragility of the ultra-thin LiNbO3 plate is problematic. In this study, the feasibility of solidly mounted resonator type SH0 mode plate wave resonator was investigated systematically by finite element method simulation. The design parameters including the Euler angle, thickness of a LiNbO3 plate, and the material and thickness of an interdigital transducer were optimized. With the best design, a BW as wide as 26% is obtained.

Ultra-wideband ladder filter using SH(0) plate wave in thin LiNbO(3) plate and its application to tunable filter.

A cognitive radio terminal using vacant frequency bands of digital TV (DTV) channels, i.e., TV white space, strongly requires a compact tunable filter covering a wide frequency range of the DTV band (470 to 710 MHz in Japan). In this study, a T-type ladder filter using ultra-wideband shear horizontal mode plate wave resonators was fabricated, and a low peak insertion loss of 0.8 dB and an ultra-large 6 dB bandwidth of 240 MHz (41%) were measured in the DTV band. In addition, bandpass filters with different center frequencies of 502 and 653 MHz at 6 dB attenuation were numerically synthesized based on the same T-type ladder filter in conjunction with band rejection filters with different frequencies. The results suggest that the combination of the wideband T-type ladder filter and the band rejection filters connected with variable capacitors enables a tunable filter with large tunability of frequency and bandwidth as well as large rejection at the adjacent channels of an available TV white space.

Ultra-wideband and high frequency resonators using shear horizontal type plate wave in LiNbO3 thin plate

A cognitive radio system requires a tunable filter with a wide tunable range to compose a simple front-end. Because the tunable range is limited by the bandwidth (BW) of resonators, an ultra-wideband resonator is an important device to implement the tunable filter. The authors previously obtained low frequency resonators with a wide BWs of 26 to 29% and a large impedance ratios of 92 to 98 dB between resonance (fr) and anti-resonance frequencies (fa) using 0-th mode shear horizontal (SH0 mode) plate wave in a LiNbO3 plate. Also, a tunable filter with the tunable range of 13% was demonstrated. However, the frequency (fr =1.8 MHz and fa = 2.3 MHz) is too low for modern wireless communication. Also, the resonators suffered from ripples due to transverse mode between fr and fa. In this study, high frequency SH0 mode plate wave resonators (fr = 430–560 MHz and fa = 530–670 MHz) with a wide bandwidth and a large impedance ratio have been fabricated using an ultrathin LiNbO3 plate. The ripples were suppressed by an apodized interdigital transducer.

1J3-4 Solidity mounted plate wave resonator with wide bandwidth using 0-th shear horizontal mode in LiNbO_3 plate(Piezoelectric Devices)

1J3-4 Solidity mounted plate wave resonator with wide bandwidth using 0-th shear horizontal mode in LiNbO_3 plate(Piezoelectric Devices)

Tunable filters using wideband elastic resonators

Currently, an ultra-wideband resonator is greatly needed to realize a tunable filter with a wide tunable range, because mobile phones with multiple bands and cognitive radio systems require such tunable filters to simplify their circuits. Although tunable filters have been studied using SAW resonators, their tunable range was insufficient for the filters even when wideband SAW resonators with a bandwidth of 17% were used. Therefore, the fabrication of wider-bandwidth resonators has been attempted with the goal of realizing tunable filters with wide tunable ranges. In this study, an SH0- mode plate wave resonator in a 27.5°YX-LiNbO3 plate with an ultra-wide bandwidth of 29.1%, a high impedance ratio of 98 dB, and a high Q (Q(r) = 700 and Q(a) = 720) was realized. Two types of tunable filters were constructed using such SH0-mode resonators and capacitors. As a result, tunable ranges (bands) of 13% to 19% were obtained. The possibility of applying the SH0-mode resonator in the high-frequency gigahertz range is discussed.

Ultrawide-Band Resonators Using Shear Horizontal-Type Plate Wave and Their Application

Currently, mobile or smart phones with multibands and a cognitive radio system require a tunable filter with a wide tunable range to simplify their circuits. An ultrawide-band resonator is an important device to realize the tunable filter. The relative bandwidths (BWs) of 12 to 17% of previously reported surface acoustic wave (SAW) resonators are not sufficient to realize the tunable filter. This time, the authors studied an SH0 mode plate wave in a LiNbO3 plate. As a result, plate wave resonators with a large electro-mechanical coupling factor (k2) of 0.55 (55%), an ultrawide bandwidth of 29%, a high Q of 700, and a large impedance ratio of 98 dB between resonance (fr) and anti-resonance (fa) frequencies were realized for the first time using 27.5–30°YX-LiNbO3 plates. Applying these resonators to a ladder-type tunable filter, a wide tunable range of 19% was obtained.

Sensing liquid density using resonant flexural plate wave devices with sol–gel PZT thin films

This study presents the design, fabrication and possible applications in liquid density sensing and biosensing of a flexure plate wave (FPW) resonator using sol–gel-derived lead zirconate titanate ...

Sensing liquid density using resonant flexural plate wave devices with sol–gel PZT thin films

This study presents the design, fabrication and possible applications in liquid density sensing and biosensing of a flexure plate wave (FPW) resonator using sol–gel-derived lead zirconate titanate (PZT) thin films. The resonator has a two-port structure with a reflecting grating on a composite membrane of PZT and SiNx. The design of the reflecting grating is derived from a SAW resonator model using COM theory to generate a sharp resonant peak. A comparison between the theoretical mass and the viscosity effects reveals the applications and the constraints of the proposed device in liquid sensing. Multiple coatings of sol–gel-derived PZT films are employed because of the cost advantage and the strong electromechanical coupling effect over other piezoelectric films. Issues of fabrication of the proposed material structure are addressed. Theoretical estimates of the mass and the viscosity effects are compared with the experimental values. The resonant frequency relates quite linearly to the density of low-viscosity liquids, revealing the feasibility of the proposed device.

Detection of proteins and intact microorganisms using microfabricated flexural plate silicon resonator arrays

We are developing biosensor arrays that are based on microfabricated silicon flexural plate wave (FPW) resonators coated with molecular recognition chemistry. The resonators within the micro-chemical analysis array (μCANARY) are micro-electromechanical (MEM) sensors that have been miniaturized to allow many independently addressable sensors to be integrated within a single silicon chip. The target analyte of an individual sensor within the chip is selectively detected by depositing molecular recognition component (or “coating”) onto the sensor surface, and monitoring changes in the frequency and phase of the resonance as the coating interacts with the analyte. The ultimate goal of this project is integration of hundreds of miniature resonators within a single chip for detection of biological species. As proof of concept demonstration, we describe here the detection of proteins and intact microorganisms using 2-element and 8-element μCANARY sensor chips and address electronics. Preliminary results of sensitivity, selectivity, and surface regeneration methods of the sensor are presented. Detection of proteins and microorganisms with the μCANARY sensor were confirmed by optical measurements.

Pressure sensing with a flexural plate wave resonator

A silicon nitride membrane supported on a silicon substrate and having a sealed air cavity underneath has been used as a pressure sensor. Membrane resonances are excited and detected using conductor lines patterned on the membrane in combination with an applied magnetic field. The resonant frequency depends strongly upon membrane tension and thus the differential pressure across the membrane.

Magnetically-excited flexural plate wave resonator

A flexural plate wave (FPW) resonator was constructed by patterning current lines on a silicon nitride membrane suspended on a rectangular silicon frame. Eigenmodes of the rectangular membrane were excited using Lorentz forces generated between alternating surface currents and a static in-plane magnetic field. The magnetic field strength required for these devices can be achieved with small permanent magnets (/spl ap/1 cm/sup 3/). Preferential coupling to a particular membrane mode was achieved by positioning current lines along longitudinal mode antinodes. An equivalent-circuit model was derived that characterizes the input impedance of a one-port device and the transmission response of a two-port device over a range of frequencies near a single membrane resonance. Experiments were performed to characterize the effects of varying magnetic field, ambient gas, gas pressure, and input power. To our knowledge, this is the first experimental demonstration of a resonant FPW device.

Flexural plate wave resonator excited with Lorentz forces

A flexural plate wave resonator was constructed by patterning current lines on a silicon nitride membrane suspended on a rectangular silicon frame. Eigenmodes of the rectangular membrane were excited using Lorentz forces generated between alternating surface currents and a static in-plane magnetic field. Preferential coupling to a particular membrane mode was achieved by positioning current lines along longitudinal mode antinodes. An equivalent-circuit model was derived which characterizes the input impedance of a one-port device and the transmission response of a two-port device over a range of frequencies near a single membrane resonance. Experiments were performed to characterize the device’s response to changes in dc magnetic field strength, ambient gas composition, gas pressure, and input power.