US5654680A
Expired / Lapsed
US
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Saw-based ladder filter including multiple coUpling coefficients (K2), Method therefor and radio incorporating same
Assignee: CTS Corp
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Filing: 1996-01-30
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Granted: 1997-08-05
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Expires: 2016-01-30
Abstract
Abstract A full duplex radio (10) having improved properties obtained by using surface acoustic wave (SAW) filters (92, 100, 100') having asymmetric frequency responses (76', 76", 140). The filters (92, 100, 100') are composed of series (50 1 , 50 1 ') and parallel (50 2 , 50 2 ') coupled SAW resonators. Asymmetry is obtained by altering the metallization thickness of either of the series (50 1 , 50 1 ') or parallel (50 2 , 50 2 ') resonators of each filter (92, 100, 100') to increase or decrease the SAW coupling coefficient of some of the resonators (50 1 , 50 1 ', 50 2 , 50 2 ') relative to the remainder of the resonators (50 1 , 50 1 ', 50 2 , 50 2 '). The filters (92, 100, 100') are desirably in pairs arranged with mirror image frequency asymmetry such that the steeper skirts (93, 95) of the frequency responses (76', 76", 140) are adjacent. Greater passband bandwidths (91', 91") can be obtained without adverse affect on transmitter and receiver isolation.
Inventors
- 👤 Philip Pak-Lin Kwan
- 👤 Ali-Reza Baghai-Wadji
- 👤 David Penunuri
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 01:11
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H03H9/64; H03H9/6423; H03H9/6433; H03H9/6483; H03H9/0023; H03H9/0028; H03H9/6406; H03H9/02; H03H9/125; H03H9/145; H03H9/14517; H03H9/1452
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
74 words
A filter utilizing surface acoustic wave (SAW) resonators, comprising, series coupled SAW resonators having first SAW coupling coefficients associated with one or more of said series coupled SAW resonators, and parallel coupled SAW resonators having second SAW coupling coefficients associated with one or more of said parallel coupled SAW resonators, wherein said series and parallel coupled SAW resonators are coupled to form said filter and said first and second SAW coupling coefficients are different.
Claim 2
Dependent Claim
74 words
A filter utilizing surface acoustic wave (SAW) resonators, comprising, series coupled SAW resonators having first SAW coupling coefficients associated with one or more of said series coupled SAW resonators, and parallel coupled SAW resonators having second SAW coupling coefficients associated with one or more of said parallel coupled SAW resonators, wherein said series and parallel coupled SAW resonators are coupled to form said filter and said first and second SAW coupling coefficients are different.
Claim 3
Dependent Claim
21 words
A filter as claimed in claim 1 wherein said series and parallel coupled SAW resonators are formed on a common substrate.
Claim 4
Dependent Claim
22 words
A filter as claimed in claim 2 wherein said series and parallel coupled SAW resonators are formed on a common piezoelectric substrate.
Claim 5
Dependent Claim
35 words
A filter as claimed in claim 3 wherein said common piezoelectric substrate is chosen from a group consisting of forty-one degree y-rotated lithium niobate, sixty-four degree y-rotated lithium niobate and thirty-six degree y-rotated lithium tantalate.
Claim 6
Dependent Claim
112 words
A filter utilizing surface acoustic wave (SAW) resonators, comprising, series coupled SAW resonators having first SAW coupling coefficients associated with one or more of said series coupled SAW resonators, and parallel coupled SAW resonators having second SAW coupling coefficients associated with one or more of said parallel coupled SAW resonators, wherein said series and parallel coupled SAW resonators are coupled to form said filter and said first and second SAW coupling coefficients are different, wherein one or more of said series coupled SAW resonators or one or more of said parallel coupled SAW resonators, have a different metellization thickness from that of a remainder of said series or parallel coupled SAW resonators.
Claim 7
Dependent Claim
112 words
A filter utilizing surface acoustic wave (SAW) resonators, comprising, series coupled SAW resonators having first SAW coupling coefficients associated with one or more of said series coupled SAW resonators, and parallel coupled SAW resonators having second SAW coupling coefficients associated with one or more of said parallel coupled SAW resonators, wherein said series and parallel coupled SAW resonators are coupled to form said filter and said first and second SAW coupling coefficients are different, wherein one or more of said series coupled SAW resonators or one or more of said parallel coupled SAW resonators, have a different metellization thickness from that of a remainder of said series or parallel coupled SAW resonators.
Claim 8
Dependent Claim
100 words
A radio incorporating surface acoustic wave (SAW) resonators on a common substrate, said radio comprising first series coupled SAW resonators and first parallel coupled SAW resonators, wherein one or more of said first series coupled SAW resonators have first SAW coupling coefficients, one or more of said first parallel coupled SAW resonators have second SAW coupling coefficients, and said first and second SAW coupling coefficients are different, wherein one or more of said first series coupled SAW resonators or one or more of said second parallel coupled SAW resonators comprise a first group of resonators having a first metallization thickness.
Claim 9
Dependent Claim
100 words
A radio incorporating surface acoustic wave (SAW) resonators on a common substrate, said radio comprising first series coupled SAW resonators and first parallel coupled SAW resonators, wherein one or more of said first series coupled SAW resonators have first SAW coupling coefficients, one or more of said first parallel coupled SAW resonators have second SAW coupling coefficients, and said first and second SAW coupling coefficients are different, wherein one or more of said first series coupled SAW resonators or one or more of said second parallel coupled SAW resonators comprise a first group of resonators having a first metallization thickness.
Claim 10
Dependent Claim
41 words
A radio as claimed in claim 6, further comprising second series coupled SAW resonators or second parallel coupled SAW resonators, wherein said second series or parallel coupled SAW resonators have second SAW coupling coefficients different than said first SAW coupling coefficients.
Claim 11
Dependent Claim
28 words
A radio as claimed in claim 6 wherein said first series coupled SAW resonators and said second parallel coupled SAW resonators are formed on a common piezoelectric substrate.
Claim 12
Dependent Claim
37 words
A radio as claimed in claim 8, wherein said common piezoelectric substrate comprises a material chosen from a group consisting of forty-one degree y-rotated lithium niobate, sixty-four degree y-rotated lithium niobate and thirty-six degree y-rotated lithium tantalate.
Claim 13
Dependent Claim
33 words
A radio as claimed in claim 6, wherein a second group comprising a remainder of said series and parallel coupled SAW resonators have a second metallization thickness different than said first metallization thickness.
Claim 14
Dependent Claim
112 words
A radio incorporating surface acoustic wave (SAW) resonators, said radio comprising a first filter with first series coupled SAW resonators with first SAW coupling coefficients and second parallel coupled SAW resonators with second SAW coupling coefficients, and a second filter with third series coupled SAW resonators with third SAW coupling coefficients and fourth parallel coupled SAW resonators with fourth SAW coupling coefficients, wherein a first ratio of said first SAW coupling coefficients divided by said second SAW coupling coefficients has a first value and a second ratio of said third SAW coupling coefficients divided by said fourth SAW coupling coefficients has a second value and said first and second values are different.
Claim 15
Dependent Claim
112 words
A radio incorporating surface acoustic wave (SAW) resonators, said radio comprising a first filter with first series coupled SAW resonators with first SAW coupling coefficients and second parallel coupled SAW resonators with second SAW coupling coefficients, and a second filter with third series coupled SAW resonators with third SAW coupling coefficients and fourth parallel coupled SAW resonators with fourth SAW coupling coefficients, wherein a first ratio of said first SAW coupling coefficients divided by said second SAW coupling coefficients has a first value and a second ratio of said third SAW coupling coefficients divided by said fourth SAW coupling coefficients has a second value and said first and second values are different.
Claim 16
Dependent Claim
61 words
A radio as claimed in claim 11 wherein said first filter has asymmetric first and second skirts, said second skirt being steeper than said first skirt, and said second filter has asymmetric third and fourth skirts, said third skirt being steeper than said fourth skirt, wherein said second and third skirts are closer in frequency than said first and fourth skirts.
Claim 17
Dependent Claim
118 words
A radio comprising transmit and receive surface acoustic wave (SAW) filters, said radio operating with transmitter frequency F trans and receiver frequency F rec , wherein when: F rec /F trans <1, receive SAW filters have C 1 /C 2 <1 and transmit SAW filters have C 1 /C 2 >1; and F trans /F rec <1, said transmit SAW filters have C 1 /C 2 <1 and said receive SAW filters have C 1 /C 2 >1, wherein C 1 is a SAW coupling coefficient of series coupled resonators making up said transmit or receive SAW filters and C 2 is a SAW coupling coefficient of parallel coupled resonators making up said transmit or receive SAW filters.
Claim 18
Dependent Claim
118 words
A radio comprising transmit and receive surface acoustic wave (SAW) filters, said radio operating with transmitter frequency F trans and receiver frequency F rec , wherein when: F rec /F trans <1, receive SAW filters have C 1 /C 2 <1 and transmit SAW filters have C 1 /C 2 >1; and F trans /F rec <1, said transmit SAW filters have C 1 /C 2 <1 and said receive SAW filters have C 1 /C 2 >1, wherein C 1 is a SAW coupling coefficient of series coupled resonators making up said transmit or receive SAW filters and C 2 is a SAW coupling coefficient of parallel coupled resonators making up said transmit or receive SAW filters.
Claim 19
Independent Claim
96 words
A method for making SAW filters having asymmetric frequency characteristics, said method comprising steps of: providing an substrate suitable for acoustic wave propagation; disposing series coupled SAW resonators having first SAW coupling coefficients associated with one or more of said series coupled SAW resonators on said substrate; and disposing parallel coupled SAW resonators having second SAW coupling coefficients associated with one or more of said parallel coupled SAW resonators on said substrate, wherein said series and parallel coupled SAW resonators are coupled to form said filter and said first and second SAW coupling coefficients are different.
Claim 20
Independent Claim
96 words
A method for making SAW filters having asymmetric frequency characteristics, said method comprising steps of: providing an substrate suitable for acoustic wave propagation; disposing series coupled SAW resonators having first SAW coupling coefficients associated with one or more of said series coupled SAW resonators on said substrate; and disposing parallel coupled SAW resonators having second SAW coupling coefficients associated with one or more of said parallel coupled SAW resonators on said substrate, wherein said series and parallel coupled SAW resonators are coupled to form said filter and said first and second SAW coupling coefficients are different.
Claim 21
Dependent Claim
26 words
A method as claimed in claim 14 wherein said disposing steps include steps of disposing said series and parallel coupled SAW resonators on a common substrate.
Claim 22
Dependent Claim
29 words
A method as claimed in claim 15 wherein said disposing steps include steps of disposing said series and parallel coupled SAW resonators are formed on a common piezoelectric substrate.
Claim 23
Dependent Claim
45 words
A method as claimed in claim 16 wherein said step of providing a substrate includes a step of providing a common piezoelectric substrate chosen from a group consisting of forty-one degree y-rotated lithium niobate, sixty-four degree y-rotated lithium niobate and thirty-six degree yrotated lithium tantalate.
Claim 24
Dependent Claim
52 words
A method as claimed in claim 14 wherein said disposing steps include steps of disposing one or more of said series coupled SAW resonators or one or more of said parallel coupled SAW resonators having a different metallization thickness from that of a remainder of said series or parallel coupled SAW resonators.
Claim 25
Dependent Claim
52 words
A method as claimed in claim 17 wherein said disposing steps include steps of disposing one or more of said series coupled SAW resonators or one or more of said parallel coupled SAW resonators having a different metallization thickness from that of a remainder of said series or parallel coupled SAW resonators.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-08-04 | 2001-02-03 | 2001-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-08-04 | 2005-02-03 | 2005-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-08-04 | 2009-02-03 | 2009-08-05 | $7700.00 | Window Closed / Lapsed |