Trw Limited

Kuo-Hsiung Yen

Robert Bruce Stokes

Kei-Fung Lau

Reynold S Kagiwada

Alvin M Kong

Marshall Y Huang

Jeffrey H Elliott

Michael J Delaney

Donald L Lochhead

Albert J Grote

Kei F Lau

David Penunuri

Ronald D Kasparek

Ke-Li Wang

Steven E Housholder

James A Leaverton

An adjustable surface acoustic wave (SAW) transducer is fabricated on a piezoelectric substrate. The adjustable SAW transducer includes a plurality of SAW interdigital transducer (IDT) fingers disposed on the substrate. Miniature switches are used to provide a plurality of interconnection patterns between the SAW IDT fingers such that a plurality of SAW characteristics can be generated from a single set of SAW IDT fingers.

Adjustable saw device

A surface acoustic wave (SAW) chirp signal processor having a piezoelectric substrate, an array of input transducers and an array of output transducers. In its chirp compression mode, the device has chirp signals applied in parallel to its input transducers and produces compressed output pulses at its output transducers, corresponding to selected chirp rates. The input transducers are successively offset with respect to a focal point on the array of output transducers, by distances that successively and linearly increase or decrease from transducer to transducer, consistent with the increase or decrease in the wavelength of the chirp signals. The device may also be used in a pulse expansion mode, by inputting a broadband pulse into a selected one of the output transducers. The input transducers then produce a chirp signal having a rate corresponding the selected to output transducer.

Surface acoustic wave chirp filter

A surface acoustic wave (SAW) device and a related method, for providing improved frequency response characteristics from a SAW spectrum analyzer or channelizer. The device includes a spectrum analyzer with a preprocessing SAW device configured to provide output signals with narrower passbands, lower sidelobe components, or both. The preprocessing SAW device is a tapped delay line in one embodiment, to simulate positional offsets in the placement of input transducers of the analyzer. The tapped delay line can also be used to provide amplitude weighting or can be configured in a chirp spacing, to transform the spectrum analyzer into a chirp analyzer. Another embodiment employs a thinned-electrode prefilter as the preprocessing device, to yield a frequency response with multiple narrow passbands, which are used to narrow the individual channel passbands of the spectrum analyzer or to suppress sidelobes in the frequency response.

Saw channelized filters

A magnetostatic wave (MSW) device for performing spectral analysis of an input signal containing signal components of very high frequency, well in excess of 1 GHz (gigahertz). An input transducer array couples the input signal to a magnetostatic propagating medium, such as a film of yttrium-iron-garnet (YIG), in such a manner that the array effectively provides multiple wave sources spaced along a predetermined arc on the propagating medium, and the waves combine constructively at frequency-dependent points in a focal region of the medium, spaced apart from the input array. Output transducers located at these frequency-dependent points generate output signals indicative of various selected frequency components of the input signal.

Magnetostatic wave channelizer

A surface acoustic wave (SAW) diffraction-effect or interference-effect device with a highly isotropic substrate having a high coupling coefficient and low attenuation losses. The use of X-propagating rotated-Y-cut lithium niobate as the SAW substrate, with the Y rotation angle selected at 121 degrees, provides a practically isotropic material, with a high coupling coefficient and relatively low attenuation losses.

Isotropic acoustic wave substrate

A surface acoustic wave (SAW) device, and corresponding method, for expanding or contracting the time scale of an input signal that varies in time but is limited to a predetermined time interval. One embodiment of the invention achieves time expansion or compression by means of two Fourier transformations providing different chirp rates, and implemented in a form that includes only five SAW dispersive delay lines. In the illustrative version of this embodiment, three of the dispersive delay lines are used in conjunction with multipliers or mixers, and two are used as convolvers. Another embodiment of the invention uses only three SAW dispersive delay lines, two in conjunction with multipliers and one located between the multipliers to effect the desired time-scale change. A third embodiment of the invention employs a SAW tapped delay line and an associated set of gates to select successive data bit signals from successive output taps in the delay line. A SAW fill-in filter is used to fill in inter-bit gaps resulting from the use of the tapped delay line.

Surface acoustic wave device for data rate reduction

An acoustic wave filter device with low loss and low passband ripple characteristics. The filter comprises three bidirectional electroacoustical transducers disposed along a common axis on the surface of a substrate of piezoelectric material. The two outer transducers of the three function as input transducers and the center transducer functions as an output transducer. One of the input transducers is of the antisymmetric type and has a transfer characteristic that differs in phase angle by ninety degrees with respect to the other input transducer, which is of the symmetric type. This ninety-degree difference applies at all frequencies, so that any energy reflected from the output transducer and again reflected by an input transducer will be subject to a phase shift of 180 degrees in the case of energy reflected from the antisymmetric input transducer, and no phase shift in the case of the symmetric input transducer. Accordingly, these triple-transit echoes will cancel at the output transducer, for all frequencies. For the primary energy propagation from the input transducers to the output transducer, a ninety-degree phase shifter in one input circuit ensures that the signals from the two input transducers are in phase when they reach the output transducer.

Low-loss acoustic wave filter device

A surface acoustic wave (SAW) device configured to operate as a spectrum analyzer, and having an array of input transducers disposed on a substrate in such positions as to produce a focused beam of acoustic energy at a focal arc, each position on the arc being representative of an input signal frequency. Output transducers produce electrical signals corresponding to the energy received at successive segments of the focal arc. The disclosed device includes various combinations of input transducer array improvements, some of which are to provide amplitude weighting of the input array, including aperture width weighting, capacitive weighting, resistive weighting, series-parallel weighting, and source withdrawal weighting. Another improvement in input array configuration eliminates close or overlapping electrodes of opposite polarities and thereby reduces parasitic capacitance and acoustic radiation between electrode elements. The use of curved input transducer fingers improves operation of the transducers as point sources. Other important improvements include the use of acoustic transducers before to transmit the focused output energy from the focal line to conventional output transducers, thereby improving frequency resolution, and the use of electromagnetic waveguides to transmit energy from output transducers located on the focal line.

Surface acoustic wave spectrum analyzer

Acoustic wave devices employing shallow bulk acoustic waves rather than surface acoustic waves, to provide higher frequencies of operation and other significant advantages, such as less susceptibility to aging and less sensitivity to surface contamination. In each embodiment of the invention, a transmitting transducer and a receiving transducer are oriented on the surface of an anisotropic piezoelectric crystal to achieve substantial coupling of shallow bulk acoustic waves and essentially zero coupling of surface acoustic waves. In one embodiment of the invention, various types of grating filters utilize shallow bulk acoustic waves, and a set of parallel mechanical or electrical discontinuities at or near the surface of the crystal provide reflection of acoustic energy at a frequency determined by the spacing of the discontinuities. Uniformly spaced gratings provide bandpass filter operation, and gratings with graduated spacings provide for frequency compression or expansion. In another embodiment of the invention, variations in device characteristics due to temperature changes are compensated for by directing the shallow bulk waves through materials having favorable or opposite temperature characteristics compared with those of the material into which the waves are originally launched. In other embodiments of the invention, a shallow bulk acoustic wave includes a multistrip coupler, for transferring electroacoustic energy from one propagation path to another, for use in bandpass filters, delay lines or unidirectional transducers.

Shallow bulk acoustic wave devices

Energy trapping elements for use with shallow bulk acoustic wave devices of various kinds, to minimize the insertion loses in such devices due to spreading of electroacoustic energy into the crystal substrate upon which the devices are constructed. Electroacoustic energy propagated in a substrate is trapped close to the surface of the substrate by means of trapping elements comprising a plurality of strips or grooves disposed on the surface of the substrate in the path of the propagated energy, and oriented approximately perpendicularly to the direction of propagation. The spacing of the elements is such that their stop-band frequency, at which energy will be reflected, is substantially different from the characteristic center frequency of the entire device, in order that the elements will serve a purely trapping function and not a reflecting function.

Shallow bulk acoustic wave devices employing energy trapping

A surface acoustic resonator including an interdigital transducer configured to generate acoustic waves at at least one harmonic frequency, and a pair of reflection gratings capable of essentially total reflection of the acoustic waves in both fundamental and harmonic modes of operation. One-port and two-port resonators are disclosed, capable of operation at fundamental and harmonic frequencies, to provide a higher frequency of operation without correspondingly higher resolution requirements for manufacturing processes. For single-mode operation at higher frequencies, the interdigital transducer and reflection gratings have different fundamental frequencies, and utilize harmonics of different order but the same actual frequency, such that the resonator functions at a single frequency, which may be, for example, the third harmonic with respect to the transducer fundamental frequency, and the second harmonic with respect to the reflection grating-fundamental frequency.

Surface acoustic wave resonators utilizing harmonic frequencies

A surface acoustic wave filter device having an input transducer and an output transducer, in which triple transit effects are minimized by the addition of a second output transducer spaced from the input transducer, preferably by a distance three times the spacing between the normal input and output transducers, to duplicate the triple transit path length. A triple transit signal is thereby simulated at the second output transducer, is adjusted in amplitude and phase, and is applied to a summing circuit in which the simulated triple transit signal is subtracted from a signal derived from the original output transducer, to effectively cancel the triple transit component.

Growing community of inventors

Manhattan Beach, CA, United States of America

Kuo-Hsiung Yen