Siemens Aktiengesellschaft

Richard Veith

Peter Zibis

Gerd Riha

Helmut Stocker

Ekkehard Ehrmann-Falkenau

Wolfgang Till

An acoustic wave filter comprising a piezoelectric substrate body upon which at least two digital structures are formed and which comprise input and output transducers and at least one further digital structure and wherein the filter digital structure has a center frequency of f.sub.2 and wherein the pass band of said two digital structures is at least twice as broad banded as said further digital structure and where the center frequencies f.sub.1 and f.sub.2 of the two digital structures are shifted relative to each other and relative to the center frequency f.sub.2 of the further digital structure.

Acoustic wave filter

A surface wave filter having an interdigital structure in which last active fingers of a first comb structure, which is to be connected to ground, extend as close as possible to a busbar of an opposite comb structure. Interference signals based on the discontinuity of the end of the interdigital structure are eliminated.

Electrical filter operating with acoustic waves

A surface wave filter (1, 11, 21, 31, 41) having a shielding structure (13, 23, 33, 43, 53) arranged between the inter-digital, asymmetrically operating structures (2, 3), which encompasses two such sub-structures (14, 24, 34, 44, 44a) and/or (15, 25, 35, 45, 35a), which are individually connected with the finger structures of the adjacent transducer structure (2 and/or 3) that are at reference ground potential.

Electric filter employing acoustic waves

In an electronic component having reflecting structures on a substrate body and functioning with reflected acoustic waves traveling thereon, at least one longitudinal lateral edge of the substrate body is aligned at an angle .delta. deviation from a direction parallel relative to an acoustic wave emitted by an input transducer. The dimension of the angle .delta. depends on the arrangement of an output transducer. This construction minimizes the appearance of spurious signals.

Electronic component functioning with reflected acoustic waves

A pulse compression filter designed as a dispersive delay line functions with acoustic waves having a mean wavelength .lambda..sub.o in the filter. At least one input/output transducer or at least one reflector arrangement is provided with a plurality of electrode respectively reflector fingers distributed on a substrate in accordance with a prescribed transfer function which has a given bandwidth and whose Fourier transform has a given time duration T. Said fingers are divided into a plurality of N finger groups designed identical to one another with respect to the number fingers n and corresponding finger spacings of corresponding fingers. Each finger group has a length in a propagation direction of the acoustic wave in the filter which is at least equal to the mean wavelength .lambda..sub.o. Center spacings of adjacent finger groups from one another are non-equidistant in accordance with the prescribed transfer function. The plurality N of the finger groups is greater than the time bandwidth duration product (T.multidot.B).

Pulse compression filter designed as a dispersive delay line

Process for the production of a piezoelectric body which contains a ferroelectric material which may be polarized in an aligned, permanent fashion and also contains a bonding material, the process comprises mixing a bonding material selected so that at least in a temperature range below the Curie temperature of the ferroelectric material, it has a specific electric conductivity .sigma..sub.B &gt; E.sub.C .times. .sigma..sub.K /E.sub.B, where .sigma..sub.K is the specific conductivity of the ferroelectric material, E.sub.C is the coercivity field strength of the ferroelectric material, and E.sub.B is the electric breakdown field strength of the bonding material with a granular ferroelectric material having a known Curie temperature, forming a desired body shape from such mixture, heating the resultant body to a temperature at least sufficient for the bonding material to exhibit its specific conductivity and applying an electric voltage of sufficient intensity to the body to produce a permanent polarization alignment in the ferroelectric material within such body.

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Unterhaching, Germany

Richard Veith