Patent US5726610A successfully refreshed from Google Patents.
US5726610A
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US
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Saw filter device for radio tranceiver utilizing different coupling coefficient ratios
Assignee: CTS Corp
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Filing: 1997-01-13
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Granted: 1998-03-10
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Expires: 2017-01-13
Abstract
Abstract A full duplex radio (10) having improved properties is obtained by using asymmetric surface acoustic wave (SAW) filters (70, 92, 100, 100', 112). The filters (70, 92, 100, 100', 112) are composed of series (50 1 , 50 1 ') and parallel (50 2 , 50 2 ') coupled SAW resonators. Asymmetry is obtained by covering either of the series (50 1 , 50 1 ') or parallel (50 2 , 50 2 ') resonators of each filter (70, 92, 100, 100', 112) with a dielectric layer (96) to increase the SAW coupling coefficient (Cs, Cp) of the covered resonators (50 1 ', 50 2 ') relative to the uncovered resonators (50 1 , 50 2 ). The filters (70, 92, 100, 100', 112) are desirably in pairs arranged with mirror image frequency asymmetry such that the steeper skirts (87, 79) of the frequency response (91', 91") are adjacent. Greater pass-band bandwidths (77, 77', 77") can be obtained without adverse affect on transmitter and receiver isolation.
Inventors
- 👤 Donald Eugene Allen
- 👤 Philip Pak-Lin Kwan
- 👤 David Patrick Stumbo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:49
CPC Classifications
H; H03; H03H; H03H9/00; H03H9/46; H03H9/64; H03H9/6423; H03H9/6433; H03H9/6483; H03H3/00; H03H3/007; H03H3/08
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
112 words
A filter device utilizing surface acoustic wave (SAW) resonators comprising: a first filter with first series coupled SAW resonators with a first SAW coupling coefficient and second parallel coupled SAW resonators with a second SAW coupling coefficient, and a second filter with third series coupled SAW resonators with a third SAW coupling coefficient and fourth parallel coupled SAW resonators with a fourth SAW coupling coefficient, wherein a first ratio of said first SAW coupling coefficient divided by said second SAW coupling coefficient has a first value and a second ratio of said third SAW coupling coefficient divided by said fourth SAW coupling coefficient has a second value different than said first value.
Claim 2
Dependent Claim
112 words
A filter device utilizing surface acoustic wave (SAW) resonators comprising: a first filter with first series coupled SAW resonators with a first SAW coupling coefficient and second parallel coupled SAW resonators with a second SAW coupling coefficient, and a second filter with third series coupled SAW resonators with a third SAW coupling coefficient and fourth parallel coupled SAW resonators with a fourth SAW coupling coefficient, wherein a first ratio of said first SAW coupling coefficient divided by said second SAW coupling coefficient has a first value and a second ratio of said third SAW coupling coefficient divided by said fourth SAW coupling coefficient has a second value different than said first value.
Claim 3
Dependent Claim
23 words
The filter device as claimed in claim 1, wherein all said series and parallel coupled SAW resonators are formed on a common substrate.
Claim 4
Dependent Claim
24 words
The filter device as claimed in claim 2, wherein all said series and parallel coupled SAW resonators are formed on a common piezoelectric substrate.
Claim 5
Dependent Claim
25 words
The filter device as claimed in claim 2, wherein said common substrate is chosen from a group consisting of lithium niobate, lithium tantalate and quartz.
Claim 6
Dependent Claim
61 words
The filter device as claimed in claim 4, wherein one of (a) one or more of one of said first and third series coupled SAW resonators, and (b) one or more of one of said second and fourth parellel coupled SAW resonators include a dielectric layer disposed thereon so as to change the respective coupling coefficient of the associated SAW resonators.
Claim 7
Dependent Claim
44 words
The filter device as claimed in claim 5, wherein said dielectric layer is chosen from a group consisting of silicon dioxide, silicon monoxide, titanium dioxide, aluminum oxide (Al 2 O 3 ), magnesium oxide, silicon nitride, tantalum oxide, zinc oxide and groups II-VI compounds.
Claim 8
Dependent Claim
61 words
The filter device as claimed in claim 1, wherein one of (a) one or more of one of said first and third series coupled SAW resonators, and (b) one or more of one of said second and fourth parallel coupled SAW resonators include a dielectric layer disposed thereon so as to change the respective coupling coefficient of the associated SAW resonator.
Claim 9
Dependent Claim
44 words
The filter device as claimed in claim 7, wherein said dielectric layer is chosen from a group consisting of silicon dioxide, silicon monoxide, titanium dioxide, aluminum oxide (Al 2 O 3 ), magnesium oxide, silicon nitride, tantalum oxide, zinc oxide and group II-VI compounds.
Claim 10
Dependent Claim
165 words
A surface acoustic wave (SAW) filter device on a common substrate, said SAW filter device comprising: a transmit surface acoustic wave (SAW) filter including series and parallel coupled SAW resonators and which operates on a radio transmitter frequency F tran and a receive SAW filter including series and parallel coupled SAW resonators and which operates on a radio receiver frequency F rec , wherein: when F rec /F tran <1, the receive SAW filter has C s /C p <1 and the transmit SAW filter has (C s /C p >1, and when F trans /F rec <1, the transmit SAW filter has C s /C p <1 and the receive SAW filter has C s /C p >1, wherein C s is a corresponding SAW coupling coefficient of associated series coupled resonators making up said transmit and receive SAW filters respectively, and C p is a corresponding SAW coupling coefficient of associated parallel coupled resonators making up said transmit and receive SAW filters respectively.
Claim 11
Dependent Claim
165 words
A surface acoustic wave (SAW) filter device on a common substrate, said SAW filter device comprising: a transmit surface acoustic wave (SAW) filter including series and parallel coupled SAW resonators and which operates on a radio transmitter frequency F tran and a receive SAW filter including series and parallel coupled SAW resonators and which operates on a radio receiver frequency F rec , wherein: when F rec /F tran <1, the receive SAW filter has C s /C p <1 and the transmit SAW filter has (C s /C p >1, and when F trans /F rec <1, the transmit SAW filter has C s /C p <1 and the receive SAW filter has C s /C p >1, wherein C s is a corresponding SAW coupling coefficient of associated series coupled resonators making up said transmit and receive SAW filters respectively, and C p is a corresponding SAW coupling coefficient of associated parallel coupled resonators making up said transmit and receive SAW filters respectively.
Claim 12
Dependent Claim
118 words
The SAW filter device as claimed in claim 9, wherein: all said series coupled SAW resonators and said parallel coupled SAW resonators are formed on a common piezoelectric substrate chosen from a group consisting of lithium niobate, lithium tantalate and quartz; and one of (a) one or more of said series coupled SAW resonators in one of said transmit and receive filters, and (b) one or more of said parallel coupled SAW resonators in one of said transmit and receive filters include a dielectric layer, chosen from a group consisting of silicon dioxide, silicon monoxide, titanium dioxide, aluminum oxide (Al 2 O 3 ), magnesium oxide, silicon nitride, tantalum oxide, zinc oxide and group II-VI compounds, disposed thereon.
Claim 13
Dependent Claim
22 words
The SAW filter device resonators as claimed in claim 9 wherein all said SAW resonators are formed on a common piezoelectric substrate.
Claim 14
Dependent Claim
27 words
The SAW filter device as claimed in claim 11, wherein said common piezoelectric substrate is chosen from a group consisting of lithium niobate, lithium tantalate and quartz.
Claim 15
Dependent Claim
68 words
The SAW filter device as claimed in claim 9 wherein one of (a) one or more of said series coupled SAW resonators in one of said transmit and receive filters, and (b) one or more of said parallel coupled SAW resonators in one of said transmit and receive filters include a dielectric layer disposed thereon so as to change the respective coupling coefficient of the associated SAW resonators.
Claim 16
Dependent Claim
46 words
The SAW filter device as claimed in claim 13, wherein said dielectric layer is chosen from a group consisting of silicon dioxide silicon or monoxide, titanium dioxide, aluminum oxide (Al 2 O 3 ), magnesium oxide, silicon nitride, tantalum oxide, zinc oxide and group II-VI compounds.
Claim 17
Dependent Claim
133 words
A radio incorporating surface acoustic wave filters comprising: transmit surface acoustic wave (SAW) filters, wherein said radio includes transmitter frequency F trans and receive SAW filters, wherein said radio includes receiver frequency F rec , wherein: when F rec /F trans <1, receive SAW filters have C s /C p <l and transmit SAW filters have C s /C p >1 and when F trans /F rec <1, transmit SAW filters have C s /C p <1 and receive SAW filters have C s /C p >1, wherein C s is a corresponding SAW coupling coefficient of associated series coupled resonators making up said transmit and receive SAW filters respectively and C p is a corresponding SAW coupling coefficient of associated parallel coupled resonators making up said transmit and receive SAW filters respectively.
Claim 18
Dependent Claim
133 words
A radio incorporating surface acoustic wave filters comprising: transmit surface acoustic wave (SAW) filters, wherein said radio includes transmitter frequency F trans and receive SAW filters, wherein said radio includes receiver frequency F rec , wherein: when F rec /F trans <1, receive SAW filters have C s /C p <l and transmit SAW filters have C s /C p >1 and when F trans /F rec <1, transmit SAW filters have C s /C p <1 and receive SAW filters have C s /C p >1, wherein C s is a corresponding SAW coupling coefficient of associated series coupled resonators making up said transmit and receive SAW filters respectively and C p is a corresponding SAW coupling coefficient of associated parallel coupled resonators making up said transmit and receive SAW filters respectively.
Claim 19
Dependent Claim
145 words
A radio as claimed in claim 15, wherein: one or more of said series coupled resonators in at least one of said transmit and receive filters and one or more of said parallel coupled resonators in at least one of said transmit and receive filters are formed on a common piezoelectric substrate chosen from a group consisting of lithium niobate, lithium tantalate and quartz; and one of (a) one or more of said series coupled SAW resonators in at least one of said transmit and receive filters, and (b) one or more of said parallel coupled SAW resonators in at least one of said transmit and receive filters include a dielectric layer, chosen from a group consisting of silicon dioxide, silicon monoxide, titanium dioxide, aluminum oxide (Al 2 O 3 ), magnesium oxide, silicon nitride, tantalum oxide, zinc oxide and group II-VI compounds, disposed thereon.
Claim 20
Dependent Claim
113 words
A radio incorporating surface acoustic wave (SAW) resonators, said radio comprising: a first filter with first series coupled SAW resonators with a first SAW coupling coefficient and second parallel coupled SAW resonators with a second SAW coupling coefficient, and a second filter with third series coupled SAW resonators with a third SAW coupling coefficient and fourth parallel coupled SAW resonators with a fourth SAW coupling coefficient, wherein a first ratio of said first SAW coupling coefficient divided by said second SAW coupling coefficient has a first value and a second ratio of said third SAW coupling coefficient divided by said fourth SAW coupling coefficient has a second value different than said first value.
Claim 21
Dependent Claim
113 words
A radio incorporating surface acoustic wave (SAW) resonators, said radio comprising: a first filter with first series coupled SAW resonators with a first SAW coupling coefficient and second parallel coupled SAW resonators with a second SAW coupling coefficient, and a second filter with third series coupled SAW resonators with a third SAW coupling coefficient and fourth parallel coupled SAW resonators with a fourth SAW coupling coefficient, wherein a first ratio of said first SAW coupling coefficient divided by said second SAW coupling coefficient has a first value and a second ratio of said third SAW coupling coefficient divided by said fourth SAW coupling coefficient has a second value different than said first value.
Claim 22
Dependent Claim
61 words
The radio as claimed in claim 17 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 23
Dependent Claim
101 words
A radio as claimed in claim 17, wherein: said first series coupled SAW resonators and second parallel coupled SAW resonators are formed on a common substrate chosen from a group consisting of lithium niobate, lithium tantalate and quartz; and one of (a) one or more of said first series coupled SAW resonators and (b) one or more of said second parallel coupled SAW resonators include a dielectric layer, chosen from a group consisting of silicon dioxide, silicon monoxide, titanium dioxide, aluminum oxide (Al 2 O 3 ), magnesium oxide, silicon nitride, tantalum oxide, zinc oxide and group II-VI compounds, disposed thereon.
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