WO2003021776A1 - Octagonal electrode for crystals - Google Patents
Octagonal electrode for crystals Download PDFInfo
- Publication number
- WO2003021776A1 WO2003021776A1 PCT/US2002/020135 US0220135W WO03021776A1 WO 2003021776 A1 WO2003021776 A1 WO 2003021776A1 US 0220135 W US0220135 W US 0220135W WO 03021776 A1 WO03021776 A1 WO 03021776A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- electrode
- crystal
- polygonal
- electrode according
- octagonal
- Prior art date
Links
- 239000013078 crystal Substances 0.000 title claims abstract description 42
- 230000008878 coupling Effects 0.000 description 7
- 238000010168 coupling process Methods 0.000 description 7
- 238000005859 coupling reaction Methods 0.000 description 7
- 239000010453 quartz Substances 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/13—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials
- H03H9/132—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials characterized by a particular shape
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
- H03H9/177—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator of the energy-trap type
Definitions
- This invention relates to oscillators that provide a stable reference source or frequency in computers or other electronic equipment. Specifically, there is an electrode configuration for a crystal resonating device that provides less mode coupling and improved spurious noise suppression.
- oscillators Various devices are well known for providing a reference frequency or source. Such devices are called oscillators.
- the oscillator typically has a quartz crystal source and also has electronic compensation circuitry to stabilize the output frequency.
- Ovenized oscillators heat the oscillator to a uniform temperature to obtain a more stable output frequency.
- the oscillators have been packaged on various support structures and in housings such as metal cans.
- the quartz crystals have electrodes patterned on each side of the crystal.
- the electrodes are used to apply a voltage across the crystal.
- the electrodes are typically made by vacuum thin film depositing a metal such as gold through a mask onto the surface of the crystal.
- a typical prior art electrode configuration 10 is shown in figure 1.
- a conventional quartz crystal blank 12 has a top surface 12A and a bottom surface 12B.
- a top electrode 14 is located on top surface 12A and a bottom electrode 20 is located on bottom surface 12B.
- Top electrode 14 has a contact portion 16 and a circular central portion 18.
- bottom electrode 20 has a contact portion 22 and a circular central portion 24.
- the contact portion would be attached to another electrical contact such as a substrate pad or a crystal clip in order to make an electrical connection to another electrical circuit such as an oscillator whose frequency is desired to be stabilized.
- Another electrical contact such as a substrate pad or a crystal clip
- the area where electrodes 14 and 20 are directly overlapping each other is indicated by area 26. As the crystal frequency is increased, the required area of the electrodes decreases. In the range of 155 Mhz, the typical electrode would be approximately 0.024 inches in diameter.
- resonator design parameters effect coupling to undesired modes. Some of these are resonator dimensions, resonator contour diopter, edge bevel, electrode size and the amount of plate-back. Frequently, many of these parameters cannot be varied because of resonator electrical parameter requirements.
- the main cause of bandbreaks in quartz crystals with circular geometry is coupling via nonlinear elastic properties to one particular type of mode excited at integral multiples of flexure and face shear modes. Band break clear regions are to expected when the electrodes span a whole number of wavelengths and terminate at nodes. Circular electrodes are clearly incompatible with this criterion for the suppression of coupling.
- an electrode for a crystal that includes a crystal blank that has a top surface and a bottom surface.
- a first electrode is located on the top surface.
- the first electrode has a contact portion and a polygonal portion.
- a second electrode is located on the bottom surface.
- the second electrode has a contact portion and a polygonal portion.
- the polygonal portions of the first and second electrodes are arranged such that they oppose each other.
- Figure 1 is a top view of a prior art crystal.
- Figure 2 is a top view of the preferred embodiment of the present invention.
- Figure 3 is an alternative embodiment of the present invention.
- Figure 4 is a cross-sectional view of figure 2.
- Figure 5 is a graph of series resistance for round and octagonal crystals.
- a crystal 40 is shown.
- a conventional quartz crystal blank 12 has a top surface 12A and a bottom surface 12B.
- a top electrode 50 is located on top surface 12A and a bottom electrode 42 is located on bottom surface 12B.
- Top electrode 50 has a contact portion 52 and a polygonal portion 54.
- bottom electrode 42 has a contact portion 44 and a polygonal portion 46.
- the contact portion would be attached to another electrical contact such as a substrate pad or a crystal clip in order to make an electrical connection to another electrical circuit such as an oscillator whose frequency is desired to be stabilized.
- Polygonal portions 46 and 54 are located opposite each other on opposite sides of crystal 12. It is noted that the polygonal portions 46 and 54 have an octagonal shape. The octagonal shape of the electrode suppresses coupled modes because reflections off the circular crystal blank edge do not come back in phase and are not reinforced.
- Crystal 80 is shown. Crystal 80 is similar to crystal 40 except that polygonal portions 46 and 54 are hexagonal shaped.
- the present invention has the advantage that the polygonal electrodes produce no change in the electrical parameters of the resonator while, at the same time suppressing coupled modes.
- Figure 5 is a graph of series resistance for round 90 and octagonal 92 crystals. It can be seen that the variation in series resistance is less for the octagonal crystals than for the round crystals. This is an improvement because of improved oscillator frequency stability over the operating temperature range and operating point.
- the new electrode configuration could also be used with other resonators such as PZT resonators and other bulk wave devices.
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP02739972A EP1421685A1 (en) | 2001-08-31 | 2002-06-26 | Octagonal electrode for crystals |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/945,213 US6448699B1 (en) | 2001-08-31 | 2001-08-31 | Octagonal electrode for crystals |
US09/945,213 | 2001-08-31 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2003021776A1 true WO2003021776A1 (en) | 2003-03-13 |
Family
ID=25482794
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2002/020135 WO2003021776A1 (en) | 2001-08-31 | 2002-06-26 | Octagonal electrode for crystals |
Country Status (3)
Country | Link |
---|---|
US (1) | US6448699B1 (en) |
EP (1) | EP1421685A1 (en) |
WO (1) | WO2003021776A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3969224B2 (en) * | 2002-01-08 | 2007-09-05 | 株式会社村田製作所 | Piezoelectric resonator and piezoelectric filter / duplexer / communication device using the same |
JP4149444B2 (en) * | 2005-01-12 | 2008-09-10 | 富士通メディアデバイス株式会社 | Piezoelectric thin film resonator and filter using the same |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5903087A (en) * | 1997-06-05 | 1999-05-11 | Motorola Inc. | Electrode edge wave patterns for piezoelectric resonator |
EP1041717A2 (en) * | 1999-03-30 | 2000-10-04 | Agilent Technologies Inc | Bulk acoustic wave resonator with improved lateral mode suppression |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2994791A (en) * | 1957-05-27 | 1961-08-01 | Shinada Toshio | Electrode of a quartz oscillator |
US4123680A (en) * | 1977-05-26 | 1978-10-31 | Tyco Crystal Products, Inc. | Piezoelectric quartz crystal products and fabrication methods therefor |
JP2000138554A (en) * | 1998-11-02 | 2000-05-16 | Murata Mfg Co Ltd | Energy confinement piezoelectric resonator |
JP2001284674A (en) * | 2000-03-30 | 2001-10-12 | Taiyo Yuden Co Ltd | Piezoelectric transformer |
-
2001
- 2001-08-31 US US09/945,213 patent/US6448699B1/en not_active Expired - Fee Related
-
2002
- 2002-06-26 WO PCT/US2002/020135 patent/WO2003021776A1/en not_active Application Discontinuation
- 2002-06-26 EP EP02739972A patent/EP1421685A1/en not_active Withdrawn
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5903087A (en) * | 1997-06-05 | 1999-05-11 | Motorola Inc. | Electrode edge wave patterns for piezoelectric resonator |
EP1041717A2 (en) * | 1999-03-30 | 2000-10-04 | Agilent Technologies Inc | Bulk acoustic wave resonator with improved lateral mode suppression |
Also Published As
Publication number | Publication date |
---|---|
US6448699B1 (en) | 2002-09-10 |
EP1421685A1 (en) | 2004-05-26 |
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