Modélisation et optimisation de structures électroniques pour le conditionnement de transducteurs piézoélectriques

Abstract : This thesis deals with the electronical optimisation of an emission/reception ultrasonic chain to maximize its performances and its S/N ratio. The frequency range is from 1 MHz to 10 MHz. We study the excitation optimisation of an emitter transducer and of the signal amplification from the receiver. The test is achieved with PZT piezoceramics. In acoustic domain, the simulations obtained with electromecanical models show performances dispersions of the transducer and the glue s influence on the sensitivity. In reception, we look for reducing the noise produced by the transducer. To make it, we identify the noise sources and measure their power spectral density (PSD). The correlation between the impedance and the PSD of noise confirms the Johnson noise law produced by the transducer in our frequency range. In the 25ÊC to 70ÊC temperature range, the experimental results show that the impedance real part present a negative thermal sensitivity. In this study, the decrease of the impedance explains the thermal stability of the PSD output noise. An optimal amplifier design concludes this part. The last part concerns the optimisation of an emitter transducer excitation module. After comparing different excitation shapes, burst sin waves lead to the best performances. In fact, this shape provides electrical energy only to the fundamental frequency. To develop this solution, we propose a frequency auto-tuned generator to find the transducer s resonance frequencies. In this one, we use iterative algorithm to find minima and maxima of the transducer voltage level. This method is tested by simulating the generator s VHDL-AMS model.
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Theses
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http://docnum.univ-lorraine.fr/prive/SCD_T_2007_0033_COUTARD.pdf
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https://hal.univ-lorraine.fr/tel-01745612
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Submitted on : Wednesday, March 28, 2018 - 1:46:05 PM
Last modification on : Tuesday, March 12, 2019 - 3:52:13 PM

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Frédéric Coutard. Modélisation et optimisation de structures électroniques pour le conditionnement de transducteurs piézoélectriques. Micro et nanotechnologies/Microélectronique. Université Henri Poincaré - Nancy 1, 2007. Français. ⟨NNT : 2007NAN10033⟩. ⟨tel-01745612⟩

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