Patent US5485131A successfully refreshed from Google Patents.
US5485131A
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Transmission line filter for MIC and MMIC applications
Assignee: Motorola Solutions Inc
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Filing: 1994-10-13
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Granted: 1996-01-16
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Expires: 2014-10-13
Abstract
Abstract A transmission line filter includes first and second substantially parallel transmission lines (20, 30), with alternate ends grounded and each transmission line (20, 30) coupled through a separate capacitor (50, 60) to electrical ground. A coupling capacitor (70) connects the first and second transmission lines (20, 30). A RF output (40) coupled to the second transmission line (30) outputs a filtered RF signal in response to a RF signal input to a RF input (10) on the first transmission line (20). MIC and MMIC applications using series capacitance to allow for line length to be reduced include versions of a band pass filter (FIGS. 5, 6), band stop filter (FIG. 7), and low pass filter (FIG. 9).
Inventors
- 👤 Lyle A. Fajen
- 👤 Michael Dydyk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 09:04
CPC Classifications
H; H01; H01P; H01P1/00; H01P1/20; H01P1/201; H01P1/203; H01P1/20327; H01P1/20336; H01P1/20354; H01P1/20381
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
166 words
A transmission line filter for MIC and MMIC applications comprises: first and second transmission lines, each including a first end and a second end, wherein the first and second transmission lines are substantially parallel, the first end of the first transmission line is adjacent to the first end of the second transmission line, and the second end of the first transmission line and the first end of the second transmission line are both coupled to an electrical ground; a RF input for inputting a RF signal coupled to the first transmission line; a first capacitor coupled in series between the first end of the first transmission line and the electrical ground; a second capacitor coupled in series between the second end of the second transmission line and the electrical ground; a third capacitor coupled between the first and second transmission lines; and a RF output coupled to the second transmission line, the RF output for outputting a filtered RF signal in response to the RF signal.
Claim 2
Dependent Claim
166 words
A transmission line filter for MIC and MMIC applications comprises: first and second transmission lines, each including a first end and a second end, wherein the first and second transmission lines are substantially parallel, the first end of the first transmission line is adjacent to the first end of the second transmission line, and the second end of the first transmission line and the first end of the second transmission line are both coupled to an electrical ground; a RF input for inputting a RF signal coupled to the first transmission line; a first capacitor coupled in series between the first end of the first transmission line and the electrical ground; a second capacitor coupled in series between the second end of the second transmission line and the electrical ground; a third capacitor coupled between the first and second transmission lines; and a RF output coupled to the second transmission line, the RF output for outputting a filtered RF signal in response to the RF signal.
Claim 3
Dependent Claim
28 words
A transmission line filter as claimed in claim 1, wherein the third capacitor is centered between the first and second ends of the first and second transmission lines.
Claim 4
Dependent Claim
61 words
A transmission line filter as claimed in claim 1, wherein a length L of each of the first and second transmission lines is L=λ g /2π(tan -1 (1/ωCZ o )), where C is a capacitance of each of the first and the second capacitors and Z o is a characteristic impedance of each of the first and the second transmission lines.
Claim 5
Dependent Claim
23 words
A transmission line filter as claimed in claim 1, wherein each of the first and the second capacitors comprises a MIC interdigitated capacitor.
Claim 6
Dependent Claim
23 words
A transmission line filter as claimed in claim 1, wherein each of the first and the second capacitors comprises a MMIC interdigitated capacitor.
Claim 7
Dependent Claim
21 words
A transmission line filter as claimed in claim 1, wherein each of the first and the second transmission lines are coplanar.
Claim 8
Dependent Claim
32 words
A transmission line filter as claimed in claim 4, wherein each of the first and the second transmission lines comprises a "U" shaped section from which interdigitated portions form the third capacitor.
Claim 9
Dependent Claim
103 words
A wave guide band pass filter comprising: a perimeter ground strip; a coupling capacitor connected between a RF input and a RF output by first and second serpentine wave guides, respectively, wherein the RF input and the RF output protrude through gaps on opposite sides of the perimeter ground strip; a first interdigitated capacitor coupled between the RF input and the perimeter ground strip; and a second interdigitated capacitor coupled between the RF output and the perimeter ground strip, wherein the wave guide band pass filter produces a pass band at the RF output from a RF signal input to the RF input.
Claim 10
Dependent Claim
103 words
A wave guide band pass filter comprising: a perimeter ground strip; a coupling capacitor connected between a RF input and a RF output by first and second serpentine wave guides, respectively, wherein the RF input and the RF output protrude through gaps on opposite sides of the perimeter ground strip; a first interdigitated capacitor coupled between the RF input and the perimeter ground strip; and a second interdigitated capacitor coupled between the RF output and the perimeter ground strip, wherein the wave guide band pass filter produces a pass band at the RF output from a RF signal input to the RF input.
Claim 11
Dependent Claim
33 words
A wave guide band pass filter as claimed in claim 8, wherein the first and the second serpentine wave guides, the coupling capacitor, and the first and second interdigitated capacitors are all coplanar.
Claim 12
Dependent Claim
48 words
A wave guide band pass filter as claimed in claim 8, wherein the perimeter ground strip is substantially rectangular, the coupling capacitor is centered within an area defined by the perimeter ground strip, and the first and the second serpentine wave guides are each of substantially identical length.
Claim 13
Dependent Claim
31 words
A wave guide band pass filter as claimed in claim 8, wherein the perimeter ground strip, the coupling capacitor, the first interdigitated capacitor, and the second interdigitated capacitor comprise a MMIC.
Claim 14
Dependent Claim
142 words
A wave guide band stop filter comprising: a perimeter ground strip; a serpentine wave guide coupled between a RF input and a RF output, wherein the RF input and the RF output protrude through gaps on opposite sides of the perimeter ground strip; a first interdigitated capacitor coupled between the RF input and the perimeter ground strip; a second interdigitated capacitor coupled between the RF output and the perimeter ground strip; and a third interdigitated capacitor having a first side and a second side, wherein the first side is coupled to the RF input, to the RF output, and to a midpoint of the serpentine wave guide and the second side is coupled to the perimeter ground strip, wherein the wave guide band stop filter excludes a stop band at the RF output from a RF signal input to the RF input.
Claim 15
Dependent Claim
142 words
A wave guide band stop filter comprising: a perimeter ground strip; a serpentine wave guide coupled between a RF input and a RF output, wherein the RF input and the RF output protrude through gaps on opposite sides of the perimeter ground strip; a first interdigitated capacitor coupled between the RF input and the perimeter ground strip; a second interdigitated capacitor coupled between the RF output and the perimeter ground strip; and a third interdigitated capacitor having a first side and a second side, wherein the first side is coupled to the RF input, to the RF output, and to a midpoint of the serpentine wave guide and the second side is coupled to the perimeter ground strip, wherein the wave guide band stop filter excludes a stop band at the RF output from a RF signal input to the RF input.
Claim 16
Dependent Claim
33 words
A wave guide band stop filter as claimed in claim 12, wherein the serpentine wave guide, the first, the second, and the third interdigitated capacitors and the perimeter ground strip are all coplanar.
Claim 17
Dependent Claim
19 words
A wave guide band stop filter as claimed in claim 12, wherein the perimeter ground strip is substantially rectangular.
Claim 18
Dependent Claim
44 words
A wave guide band stop filter as claimed in claim 12, further comprising a fourth capacitor coupled between the RF input and the first side of the third interdigitated capacitor and a fifth capacitor coupled between the RF output and the third interdigitated capacitor.
Claim 19
Dependent Claim
36 words
A wave guide band stop filter as claimed in claim 12, wherein the perimeter ground strip, the serpentine wave guide, the first interdigitated capacitor, the second interdigitated capacitor, and the third interdigitated capacitor comprise a MMIC.
Claim 20
Dependent Claim
95 words
A wave guide low pass filter comprising: a perimeter ground strip; a serpentine wave guide coupled between a RF input and a RF output, wherein the RF input and the RF output protrude through gaps on opposite sides of the perimeter ground strip; a first interdigitated capacitor coupled between the RF input and the perimeter ground strip; and a second interdigitated capacitor coupled between the RF output and the perimeter ground strip, wherein the wave guide low pass filter excludes higher frequencies at the RF output from a RF signal input to the RF input.
Claim 21
Dependent Claim
95 words
A wave guide low pass filter comprising: a perimeter ground strip; a serpentine wave guide coupled between a RF input and a RF output, wherein the RF input and the RF output protrude through gaps on opposite sides of the perimeter ground strip; a first interdigitated capacitor coupled between the RF input and the perimeter ground strip; and a second interdigitated capacitor coupled between the RF output and the perimeter ground strip, wherein the wave guide low pass filter excludes higher frequencies at the RF output from a RF signal input to the RF input.
Claim 22
Dependent Claim
31 words
A wave guide low pass filter as claimed in claim 17, wherein the serpentine wave guide, the first and the second interdigitated capacitors and the perimeter ground strip are all coplanar.
Claim 23
Dependent Claim
30 words
A wave guide low pass filter as claimed in claim 17, wherein the perimeter ground strip is substantially rectangular and the serpentine wave guide is bilaterally symmetric about a midpoint.
Claim 24
Dependent Claim
32 words
A wave guide band stop filter as claimed in claim 17, wherein the perimeter ground strip, the serpentine wave guide, the first interdigitated capacitor, and the second interdigitated capacitor comprise a MMIC.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-01-15 | 1999-07-17 | 2000-01-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-01-15 | 2003-07-17 | 2004-01-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-01-15 | 2007-07-17 | 2008-01-16 | $7700.00 | Window Closed / Lapsed |