US5168253A
Expired / Lapsed
US
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High frequency ladder type piezo-electric filter with differently poled series and parallel resonators
Assignee: Niterra Co Ltd
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Filing: 1991-05-21
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Granted: 1992-12-01
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Expires: 2011-05-21
Abstract
Abstract A ladder type piezo-electric filter comprising series piezo-electric resonators and parallel piezo-electric resonators having improved second harmonic mode, high resonance response and anti-resonance impedance near 1-7 MHz, for use in communication applications requiring filter shaving resonator dimensions less than 5 mm and operating frequencies in excess of 455 kHz.
Inventors
- 👤 Yasuhiko Nakagawa
- 👤 Hisao Banno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 17:48
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H03H9/54; H03H9/56; H03H9/562; H03H9/58; H03H9/60; H03H9/605
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
388 words
A ladder type piezo-electric filter, comprising: a plurality of N series piezo-electric resonators, where N is an integer, each of said plurality of series resonators including: a piezo-electric plate having first and second sides, a central electrode provided in a central portion of the first side of the piezo-electric plate, a peripheral electrode provided on the first side of the piezo-electric plate, surrounding the central electrode, and electrically insulated from the central electrode, a common electrode provided on the second side of the piezo-electric plate, and the piezo-electric plate having a first region corresponding to the central electrode and a second region corresponding to the peripheral electrode said first region and said second region being polarized in the same direction; an input/output line electrically connecting an input terminal to a peripheral electrode of a first one of said plurality of series resonators, connecting the central electrode of an N th one of said plurality of series resonators to an output terminal, and connecting a central electrode of each one of said plurality of series resonators to a peripheral electrode of an adjacent one of said plurality of series resonators for each one of said plurality of series resonators 1 through N; a plurality of parallel piezo-electric resonators, each of said plurality of parallel resonators including: a piezo-electric plate having first and second sides, a central electrode provided in a central portion of the first side of the piezo-electric plate, a peripheral electrode provided on the first side of the piezo-electric plate, surrounding the central electrode and electrically connected to the central electrode, a common electrode provided on the second side of the piezo-electric plate, and the piezo-electric plate having a first region corresponding to the central electrode, said first region being polarized in a first direction, a second region corresponding to the peripheral electrode, said second region being polarized in a direction opposite the polarization of the first region a ground line electrically connected to the common electrode of each one of said plurality of parallel resonators; wherein the central electrode of each one of said plurality of parallel resonators is electrically connected to the input/output line at a respective point between the central electrode of each one of said plurality of series resonators and the peripheral electrode of an adjacent one of said plurality of series electrodes.
Claim 2
Dependent Claim
388 words
A ladder type piezo-electric filter, comprising: a plurality of N series piezo-electric resonators, where N is an integer, each of said plurality of series resonators including: a piezo-electric plate having first and second sides, a central electrode provided in a central portion of the first side of the piezo-electric plate, a peripheral electrode provided on the first side of the piezo-electric plate, surrounding the central electrode, and electrically insulated from the central electrode, a common electrode provided on the second side of the piezo-electric plate, and the piezo-electric plate having a first region corresponding to the central electrode and a second region corresponding to the peripheral electrode said first region and said second region being polarized in the same direction; an input/output line electrically connecting an input terminal to a peripheral electrode of a first one of said plurality of series resonators, connecting the central electrode of an N th one of said plurality of series resonators to an output terminal, and connecting a central electrode of each one of said plurality of series resonators to a peripheral electrode of an adjacent one of said plurality of series resonators for each one of said plurality of series resonators 1 through N; a plurality of parallel piezo-electric resonators, each of said plurality of parallel resonators including: a piezo-electric plate having first and second sides, a central electrode provided in a central portion of the first side of the piezo-electric plate, a peripheral electrode provided on the first side of the piezo-electric plate, surrounding the central electrode and electrically connected to the central electrode, a common electrode provided on the second side of the piezo-electric plate, and the piezo-electric plate having a first region corresponding to the central electrode, said first region being polarized in a first direction, a second region corresponding to the peripheral electrode, said second region being polarized in a direction opposite the polarization of the first region a ground line electrically connected to the common electrode of each one of said plurality of parallel resonators; wherein the central electrode of each one of said plurality of parallel resonators is electrically connected to the input/output line at a respective point between the central electrode of each one of said plurality of series resonators and the peripheral electrode of an adjacent one of said plurality of series electrodes.
Claim 3
Dependent Claim
36 words
The ladder type piezo-electric filter according to claim 1, wherein the piezo-electric plate in each of the plurality of series resonators and the piezo-electric plate in each of the plurality of parallel resonators have equal thickness.
Claim 4
Dependent Claim
60 words
The ladder type piezo-electric filter according to claim 1, wherein the central electrode of each one of the plurality of series resonators is circularly formed about a center axis on the first side of the piezo-electric plate, and wherein the peripheral electrode of each one of the N series resonators is coaxially formed in a ring surrounding the central electrode.
Claim 5
Dependent Claim
59 words
The ladder type piezo-electric filter according to claim 1, wherein the central electrode of each one of the parallel resonators is circularly formed about a center axis on the first side of the piezo-electric plate, and wherein the peripheral electrode of each one of the plurality of parallel resonators is coaxially formed in a ring surrounding the central electrode.
Claim 6
Dependent Claim
64 words
The ladder type piezo-electric filter according to claim 1, wherein the central electrode of each one of the series and parallel resonators is respectively formed about a respective center axis on the first side of each respective piezo-electric plate, and wherein the peripheral electrode of each one of the series and parallel resonators is coaxially formed in a ring surrounding the respective central electrode.
Claim 7
Dependent Claim
27 words
The ladder type piezo-electric filter according to claim 1, wherein the piezo-electric plate in each one of the plurality of series and parallel resonators is a ceramic.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-12-01 | 1996-06-01 | 1996-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-12-01 | 2000-06-01 | 2000-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-12-01 | 2004-06-01 | 2004-12-01 | $7700.00 | Window Closed / Lapsed |