Tele Filter Zweigniederlassung Der Dover Germany, Gmbh

G&uuml;nter Martin

Bert Wall

Transversally coupled resonator filter

The invention aims at modifying SPUDT-type surface acoustic wave filters in such a way that the wideband filter can be produced with lower insertion loss and a small form factor without substantially enlarging layout. According to the invention, this is achieved by combining the following characteristics: a) the totality of fingers ( ) of each transducer ( ) forms a tapering structure and b) the widths and the positions of the fingers are chosen in such a way that the waves reflected on the fingers ( ) together with the waves regenerated by the corresponding source and load resistance ( ) result in an lengthening of the impulse response of the filter, which reduces form factor and/or bandwidth. The invention can be used in surface acoustic wave-based components such as wideband bandpass filters and delay lines.

Surface acoustic wave filter

The aim of the invention is to modify prior art converters for surface acoustic waves in such a way that, despite an essentially homogeneous amplitude profile, other weighting factors can also be realized as 0 or &plusmn;1. The invention considers converters of the prior art that consist of prong groups which are comprised of at least two prongs, are arranged on a piezoelectric substrate, and which are assembled to form collector electrodes. According to the invention at least some of the prong groups are constructed in such a way that they differ from the remaining prong groups with regard to the wave amplitude excited thereby. In order to fulfil the aim of the invention, a combination of the following features is provided: a) the prongs form, in their entirety, a structure which tapers in a prong direction, and; b) at least some of the prong groups ( ), designated as structured prong groups, are subdivided, in a prong direction, into a number of subconverters ( ) and these subconverters are electrically connected in series. The invention can be used in components which function on the basis of surface acoustic waves, for example, in broadband band-pass filters and in delay lines.

Growing community of inventors

Dresden, Germany

Günter Martin

Growing community of inventors

Dresden, Germany

G&uuml;nter Martin

Günter Martin