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Browse Prior Art Database

Direct Acoustic AC Rectifier

IP.com Disclosure Number: IPCOM000079518D
Original Publication Date: 1973-Jul-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Hoechli, UT: AUTHOR

Abstract

An AC acoustic signal is converted into a DC strain, i.e., a length change by a solid exhibiting a nonlinear stress-strain characteristic. Suitable materials showing nonlinearity* are ferroelectrics (BaTiO(3)). antiferromagnetics (NiO), and distortive materials (Sr TiO(3)). Nonlinearity is caused by domain wall mobility, consequently it sets in at some minimum frequency f min. where the domain walls start to lag behind the stress, and it rises fast with frequency.

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Direct Acoustic AC Rectifier

An AC acoustic signal is converted into a DC strain, i.e., a length change by a solid exhibiting a nonlinear stress-strain characteristic. Suitable materials showing nonlinearity* are ferroelectrics (BaTiO(3)). antiferromagnetics (NiO), and distortive materials (Sr TiO(3)). Nonlinearity is caused by domain wall mobility, consequently it sets in at some minimum frequency f min. where the domain walls start to lag behind the stress, and it rises fast with frequency.

(A) Acoustic rectification into a resonator allows a highly selective analysis of an ultrasonic power spectrum P(f), due to the large quality factor Q , 10/3/ to 10/6/ of common acoustic resonators. This selectivity is maintained when either input or output strain needs to be converted into an electrical signal by the piezoelectric effect.

(B) Acoustic delay lines made of polydomain material become free of harmonic interference if operated around f min. Any harmonics generated due to nonlinearity in the electric system are rectified into a DC signal and rejected by the receiving transducer. This is of special importance for recycling delay lines. *
R. M. Bozorth, Ferromagnetism, van Nostrand, Princeton (1951), p. 685.

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