Abstract: A reactance filter includes a series branch that includes a number of series impedance elements that are coupled in series and a number of parallel branches each having a parallel impedance element coupled to a respective node of the series branch. Each impedance element includes a resonator that works with acoustic waves. The resonators in the series branch include a first piezoelectric material and the resonators in the parallel branches include a second piezoelectric material that is different than the first piezoelectric material.

Abstract: A filter circuit providing improved attenuation, a filter having improved attenuation and a duplexer with improved isolation are provided. The filter circuit has a first and a second coupling conductor segment which couple an input port to a ground port or the filter's output port. The filter circuit can be realized in the filter. The duplexer can comprise the filter, especially as its transmission filter.

Abstract: A reactance filter comprising suppression in the stop band comprises an input connection for applying an input signal, an output connection for outputting an output signal, at least series resonator, which is connected in a signal path between the input connection and the output connection, a parallel resonator, which is connected between the signal path and a connection in order to apply a reference potential, and an inductor, which is connected in series to the parallel resonator. A capacitor is connected by means of one connection between the at least one parallel resonator and the inductor and by means of the additional connection to the output connection. By connecting the reactance filter as a transmission filter in a duplexer component, the isolation in the receiving band of the duplexer component can be improved.

Abstract: A filter circuit providing improved attenuation, a filter having improved attenuation and a duplexer with improved isolation are provided. The filter circuit has a first and a second coupling conductor segment which couple an input port to a ground port or the filter's output port. The filter circuit can be realized in the filter. The duplexer can comprise the filter, especially as its transmission filter.

Abstract: A reactance filter includes a series branch that includes a number of series impedance elements that are coupled in series and a number of parallel branches each having a parallel impedance element coupled to a respective node of the series branch. Each impedance element includes a resonator that works with acoustic waves. The resonators in the series branch include a first piezoelectric material and the resonators in the parallel branches include a second piezoelectric material that is different than the first piezoelectric material.

Abstract: A reactance filter comprising suppression in the stop band comprises an input connection (1) for applying an input signal (ES), an output connection (A100) for outputting an output signal (TS), at least series resonator (11, 12, 13, 14), which is connected in a signal path (SP) between the input connection (1) and the output connection (A100), a parallel resonator (21), which is connected between the signal path (SP) and a connection (M) in order to apply a reference potential, and an inductor (31), which is connected in series to the parallel resonator (21). A capacitor (50) is connected by means of one connection (A50a) between the at least one parallel resonator (21) and the inductor (31) and by means of the additional connection (A50b) to the output connection (A100). By connecting the reactance filter as a transmission filter in a duplexer component, the isolation in the receiving band of the duplexer component can be improved.

Abstract: 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.