Filter device
OwnerShigeyuki Shiga-ken, Norio Taniguchiinventors
Life of this patent
Estimating the term…
Abstract
In a communication system including a first bandpass filter having a relatively low passband or a second bandpass filter having a relatively high passband, a filter device is used as the first bandpass filter. Series-arm resonators are inserted in a series arm connecting an input terminal and an output terminal. Parallel-arm resonators are connected in parallel arms connecting the series arm and a reference potential. Inductances are connected in series with at least one of the parallel-arm resonators. The resonant frequency of a secondary resonance generated by insertion of the inductances is within or in the vicinity of the passband of the receiver or transmitter bandpass filter serving as a partner filter of the ladder filter.
Claims20
1-8. (canceled)
A filter device for use in a communication system including a first bandpass filter having a relatively low passband frequency and a second bandpass filter having a relatively high passband frequency, the filter device defining the first bandpass filter and having a ladder circuit structure, the filter device comprising:
- at least one series-arm resonator inserted in a series arm connecting an input terminal and an output terminal;
- at least one parallel-arm resonator connected in at least one parallel arm connecting the series arm and a reference potential;
- and
- an inductance connected in series with the at least one parallel-arm resonator;
- wherein
- the inductance has an inductance value such that the frequency of a secondary resonance generated in the at least one parallel-arm resonator by inserting the inductance is within or in the vicinity of the passband of the second bandpass filter which defines a partner filter of the filter device.
A filter device for use in a communication system including a first bandpass filter having a relatively low passband frequency and a second bandpass filter having a relatively high passband frequency, the filter device defining the first bandpass filter and having a ladder circuit structure, the filter device comprising:
- three series-arm resonators inserted in a series arm connecting an input terminal and an output terminal;
- two parallel-arm resonators connected in at least one parallel arm connecting the series arm and a reference potential;
- and
- two inductances connected in series with the two parallel-arm resonators;
- wherein
- the two inductances have inductance values such that the frequency of a secondary resonance generated in the two parallel-arm resonator by inserting the inductance is within or in the vicinity of the passband of the second bandpass filter which defines a partner filter of the filter device.
Dependencies are inferred from the claim text.