EP0140462A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Temperature compensated capacitor
Assignee: Teledyne Defence Ltd
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Filing: 1984-03-26
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Granted: —
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Expires: 2004-03-26
Abstract
Abstract A temperature compensating capacitor device is described. The device incorporates at least two capacitors with different dielectric materials which vary with temperature such that the overall capacitance of the device remains substantially constant. Filter circuits incorporating such devices and methods of making them are described. Capacitors of one dielectric material are formed by etching a conductive coating on one face of a layer of that material. The layer is attached via a conductive coating on its other face to the base of a housing, and capacitors of the other dielectric material are attached to its etched face. Other impedances are attached between the capacitors to form the ladder network.
Inventors
- 👤 Christopher I. Filtronic Components Ltd. Mobbs
- 👤 David J. C/O Filtronic Components Ltd. Rhodes
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 23:16
CPC Classifications
H; H01; H01G; H01G4/00; H01G4/002; H01G4/258; H03; H03H; H03H7/00; H03H7/54; Y; Y10; Y10T; Y10T29/00; Y10T29/43; Y10T29/435
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
67 words
A capacitor device incorporating at least two different dielectric materials chosen such that one of said materials, if used alone, would cause an increase in capacitance with temperature, and the other material, if used alone, would cause a decrease in capacitance with temperature, said two materials being connected whereby to minimize a change in the capacitance across said materials as a result of a change in temperature.
Claim 2
Dependent Claim
67 words
A capacitor device incorporating at least two different dielectric materials chosen such that one of said materials, if used alone, would cause an increase in capacitance with temperature, and the other material, if used alone, would cause a decrease in capacitance with temperature, said two materials being connected whereby to minimize a change in the capacitance across said materials as a result of a change in temperature.
Claim 3
Dependent Claim
54 words
The device of claim 1, comprising at least two capacitors formed respectively from said dielectric materials between respective plates, the materials and dimensions of said capacitors being structured such that, with increasing temperature, the capacitance of a first one of said capacitors decreases and the capacitance of a second one of said capacitors increases.
Claim 4
Dependent Claim
15 words
The device of claim 2, wherein said capacitors are connected in parallel or in series.
Claim 5
Independent Claim
24 words
The device of any of claims 1 to 3 wherein said first dielectric material comprises PTFE fibres and said second dielectric material is alumina.
Claim 6
Dependent Claim
19 words
The device of claim 4, the ratio of the capacitance of the capacitors is of the order of 2.1.
Claim 7
Dependent Claim
39 words
A filter circuit for producing a desired frequency response, including at least one circuit section comprising a combination of impedances including a capacitance impedance, said capacitative impedence being a device as claimed in any of claims 1 to 5.
Claim 8
Dependent Claim
20 words
The filter circuit of claim 8, wherein said capacitative impedance includes at least two capacitor devices connected across an inductor.
Claim 9
Dependent Claim
19 words
The filter circuit of claim 7, wherein a plurality of sections are connected together to form a ladder network.
Claim 10
Dependent Claim
16 words
The filter circuit of claim 8, wherein adjacent circuit sections are connected together by coupling capacitors.
Claim 11
Dependent Claim
29 words
The filter circuit of claim 8 or 9, wherein the first and last circuit sections of said ladder formation are inductively cross-coupled together to produce a quasi-elliptic frequency response.
Claim 12
Dependent Claim
42 words
The filter circuit of claims 8 or 9 wherein said capacitors of each section are connected in series across said impedance, and adjacent circuit sections in said ladder formation are connected. together between the midpoints of the capacitors of said adjacent sections.
Claim 13
Dependent Claim
118 words
The filter circuit of any of claims 8 to 11 comprising a housing having a conductive inner face and a signal inlet and outlet, said sections being mounted in said housing between said inlet and said outlet, said first capacitors of said sections comprising a layer of said dielectric material having a coating of conductive material on one face which is attached to the base of said housing and a coating of etched conductive material on its other face, the areas of conductive material formed by the etching defining said first capacitors; said second capacitors being attached to said areas of conductive material and said impedances comprising inductors connected between said second capacitors and said housing inner wall.
Claim 14
Dependent Claim
57 words
The filter circuit of claim 12, wherein said etched face of said first dielectric material includes an etched conductive coupling line between different areas of said housing inner wall, the second capacitors of first and last sections of said ladder formation being connected by inductors to spaced points on said coupling line to form an inductive cross-coupling.
Claim 15
Dependent Claim
45 words
The filter circuit of claim 12, said second capacitors of said sections comprising a layer of said second dielectric material having a conductive coating on each face, said conductive coatings each being etched to form opposed conductive areas between which said second capacitors are defined.
Claim 16
Dependent Claim
63 words
The filter circuit of claim 14, wherein adjacent sections are connected together by conductive areas on an upper face of said second dielectric material layer extending between areas defining adjacent second capacitors so as to define a capacitor connection between the lower face of said first dielectric material layer and said extended area of said upper face of said second dielectric material layer.
Claim 17
Independent Claim
146 words
A method of.making a filter device for producing a desired frequency response, the method comprising the steps of: taking a sheet of a first dielectric material having a coating of conductive material on both faces; etching away the conductive material on one face of said sheet to define a first set of capacitors between opposed conductive areas of said faces; attaching said sheet at its unetched face to the base of a housing; attaching a second set of capacitors having a second dielectric material different to that of said first dielectric material to said conductive areas on said etched face of said sheet; arid connecting inductive impedances from said housing, respectively, to.said second set of capacitors to form a ladder type filter circuit of adjacent circuit sections each comprising one capacitor of said first set, one capacitor of said second set, and one of said impedances
Claim 18
Independent Claim
146 words
A method of.making a filter device for producing a desired frequency response, the method comprising the steps of: taking a sheet of a first dielectric material having a coating of conductive material on both faces; etching away the conductive material on one face of said sheet to define a first set of capacitors between opposed conductive areas of said faces; attaching said sheet at its unetched face to the base of a housing; attaching a second set of capacitors having a second dielectric material different to that of said first dielectric material to said conductive areas on said etched face of said sheet; arid connecting inductive impedances from said housing, respectively, to.said second set of capacitors to form a ladder type filter circuit of adjacent circuit sections each comprising one capacitor of said first set, one capacitor of said second set, and one of said impedances
Claim 19
Dependent Claim
32 words
The method of claim 16, wherein said second set of capacitors comprise individual capacitors, and one each ofsaid capacitors is attached to each conductive area defining said capacitors of said first set.
Claim 20
Dependent Claim
40 words
The method of claim 16 or 17, wherein said dielectric materials and the dimensions of said first setand said second set of capacitors are selected such that, on change in temperature the overall capacitance of each section is substantially constant.
Claim 21
Independent Claim
79 words
The method of any of claims 16 to 18, including etching a coupling line of conductive material on said etched face of said sheet, said line extending between spaced areas on an inner conductive wall of said housing when said sheet is attached to said housing, and connecting capacitors D f first and last sections of said filter circuit through inductors to spaced points on said coupling line to form an inductive cross-coupling between said first and last sections.
Claim 22
Independent Claim
40 words
The method of any of claims 16 to 19, wherein said second set of capacitors are formed by etching conductive coatings on opposite sides of a sheet of said second dielectric material to form opposed conductive areas defining said capacitors.
Claim 23
Dependent Claim
64 words
The method of claim 20, wherein coupling links between adjacent sections of said ladder circuit are formed by etching conductive areas in the uppermost coating of said second material sheet which extend between said opposed conductive areas, said links each comprising a capacitor of both dielectric materials defined between said extended areas and underlying areas of the lowermost coating of the first material sheet.
Claim 24
Independent Claim
50 words
The method of any of claims 16 to 21, wherein said sheet of said first dielectric material is attached to said base of said housing by reflow soldering and said sheet of said second dielectric material is attached to the etched face of said first material sheet by reflow soldering.
Claim 25
Independent Claim
42 words
The method of any of claims 16 to 22 wherein said second dielectric-material is alumina and said first dielectric material is a flexible material which tends to absorb the effects of thermal expansion and contraction of said housing, such as PTFE fibres.
References Cited (Backward Citations)
No citation records indexed.
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