Ngk Spark Plug Company, Limited

Tatsuo Iwata

Kazuhiro Hayashi

Tatsuo Ogawa

Yasuhiko Nakagawa

Masayuki Watanabe

A multilayer type piezoelectric filter is provided which includes at least two chambers for receiving therewithin resonators, respectively. The chambers are partly defined by a top printed circuit board and an intermediate printed circuit board. The top printed circuit board and the intermediate printed circuit board are formed with communication holes for communicating the chambers with the outside.

Multilayer piezoelectric filter with an air vent between two resonator chambers

A ladder type piezoelectric filter has a circuit configuration such that a group delay time characteristic of the filter can easily be improved. The piezoelectric filter includes six resonators, a pair of series resonators S1 and S2 connected in series between input and output terminals. A pair of parallel resonators P1 and P2 and another pair of parallel resonators P3 and P4 are respectively connected between the connection point of the series resonators S1 and S2 and a grounding terminal and between the connection point of the downstream series resonator S2 and the output terminal and the grounding terminal.

6-elements ladder type piezoelectric filter

A piezoelectric filter device having one or more pairs of piezoelectric resonators for forming a ladder-type filter circuit, a plurality of terminal plates including an input and output terminal plates for electro-mechanically holding respective resonators at oscillation nodes, and a casing for containing the piezoelectric resonators and the terminal plates and having an opening which is closed by an insulating filler, in which the opening has an inner peripheral rough surface with which the insulating filler is securly bonded. The casing has a connecting extention extending from the bottom wall thereof which is longer than cranked or bent connecting legs of the input and output terminal plates. Alternatively, each cranked or bent connecting leg has a width larger than that of its tip portion to be connected to a printed-circuit board.

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Nagoya, Japan

Tatsuo Iwata