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This article presents a procedure for the design of bulk acoustic wave (BAW) filters. The procedure consists of optimizing the modified Butterworth-Van Dyke model of each resonator, considering appropriate technological parameters. The approach is demonstrated first to design a classical aluminum nitride-based BAW filter but remains valid for other piezoelectric layers, considering either longitudinal or transverse acoustic wave coupling. The approach is finally applied to the design of a lithium niobate (LiNbO 3 ) BAW filter for wide-band filtering applications.

Two bismuth oxalates, namely, Bi(CO)·7HO and Bi(CO)OH, were studied in terms of synthesis, structural characterization, particle morphology, and thermal behavior under several atmospheres. The oxalate powders were produced by chemical precipitation from bismuth nitrate and oxalic acid solutions under controlled pH, then characterized by X-ray diffraction (XRD), temperature-dependent XRD, IR spectroscopy, scanning electron microscopy, and thermogravimetric differential thermal analyses. New results on the thermal decomposition of bismuth oxalates under inert or reducing atmospheres are provided. On heating in nitrogen, both studied compounds decompose into small bismuth particles. Thermal properties of the metallic products were investigated. The Bi(CO)OH decomposition leads to a Bi-BiO metal-oxide composite product in which bismuth is confined in a nanometric size, due to surface oxidation. The melting point of such bismuth particles is strongly related to their crystallite size. The nanometric bismuth melting has thus been evidenced ∼40 °C lower than for bulk bismuth. These results should contribute to the development of the oxalate precursor route for low-temperature soldering applications.

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-This paper describes the works performed on a solution of packaging dedicated to 3D TR modules in the 2-20GHz frequency range. The proposed solution is based on a non hermetic architecture involving organic and BCB substrates. The studied key bricks relative to assembly, vertical interconnections, passives integration are described and results consecutive to electrical and environmental evaluation are presented. A 3D TR module demonstrator taking benefit from the key bricks evaluated through test vehicles has been realised and its performances measured when submitted to airborne environmental constraints.