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Amplification of Acoustic Surface Wave Pulses

IP.com Disclosure Number: IPCOM000080602D
Original Publication Date: 1974-Jan-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 3 page(s) / 29K

Publishing Venue

IBM

Related People

Levanoni, M: AUTHOR

Abstract

Described is a simple way by which wide-band and high-strain, acoustic surface wave (ASW) pulses can be generated. The technique utilizes synchronous triggering of a multitransducer array, in which the individual transducers are connected electrically in parallel and acoustically in series.

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Amplification of Acoustic Surface Wave Pulses

Described is a simple way by which wide-band and high-strain, acoustic surface wave (ASW) pulses can be generated. The technique utilizes synchronous triggering of a multitransducer array, in which the individual transducers are connected electrically in parallel and acoustically in series.

The most efficient way of generating ASW is by an interdigital transducer fabricated on an appropriate piezoelectric substrate. Application of alter ate voltage to the interdigital electrodes, results in ASW generation. The bandwidth of such a transducer is inversely proportional to the number of electrode-pairs N, while its gain is proportional to N. The gain-bandwidth product of such a device is therefore constant. If a wide band ASW pulse is desired, N has to be small, resulting in small gain and consequently low strain.

In meny applications utilizing acousto-optic or acoustomagnetic interactions, wide band and high-strain ASW pulses are desired for practical implementations of these interactions. Since bandwidth considerations determine N the number of electrode-pairs, the only way to achieve high strain is to increase the power input of the transducer. This is normally done by wide band tuning circuits which are not compatible with planar technology, and are not easy to achieve at high frequencies. In addition, at high frequencies, electrical breakdowns between adjacent electrodes create problems at high-input voltage levels. Described is a method which bypasses the aforementioned problems.

The transducer array used in the present method is depicted in the figure. The individual transducers are connected electrically in parallel and acoustically in series. An ASW pulse, generated at the first transducer, will reach the second transducer, a distance L away, after a time interval Deltat = L/V where V is the ASW velocity.

If at that time, t...