MONOLITHIC ELECTRIC WAVE FILTERS

• US 3,576,453 A
• Filed: 05/02/1969
• Issued: 04/27/1971
• Est. Priority Date: 05/02/1969
• Status: Expired due to Term

• Current Assignee: Warren P. Mason
• Original Assignee: Warren P. Mason
• Inventors: Mason, Warren P.
• Application Number:
  US04/821,273
• Time in Patent Office: 725 Days
• US Class Current: 310/320
• CPC Class Codes: H03H 9/566 Electric coupling means therefor H03H9/0095 takes precedence

Abstract

A crystal wafer supports two or more pairs of opposing electrodes to form a monolithic crystal filter. The wafer material has a high piezoelectric coupling coefficient. Inharmonic oscillations are suppressed by plating the electrodes on the surfaces of recesses in the faces of the wafer.

Claims

2. A resonator as in claim 1 wherein said third region supports second electrode means whereby energy applied at said first electrode means may be sensed at said second electrode means.

3. A resonator as in claim 1 further comprising a plurality of additional regions each surrounded by said second region and thinner than said second region, said regions being acoustically coupled to each other through said second region when said wafer is excited in a thickness shear mode.

4. A resonator as in claim 3 wherein said first region and said plurality of additional regions form respective resonator means coupled to at least one of said other resonator means through said second region.

5. A resonator as in claim 4 wherein one of said plurality of regions supports electrode means and wherein energy applied to one of said electrode means maY be sensed by the other of said electrode means.

6. A resonator as in claim 5 wherein the remainder of said regions surrounded by said second region each support electrode means and wherein said electrode means each comprise a pair of electrode plates and wherein the plates of the electrode means on the remaining ones of said regions are short-circuited.

7. A resonator as in claim 2 wherein said resonator means when said wafer is excited in a thickness shear mode exhibit two resonant frequencies and at least one antiresonant frequency and wherein said antiresonant frequency is higher than either one of said resonant frequencies.

8. A resonator as in claim 2 wherein said resonant means exhibit when said wafer is excited in the thickness shear mode two resonant frequencies and two antiresonant frequencies and wherein said resonant frequencies are each lower in frequency than each of said antiresonant frequencies.