US3758884A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Band-rejection filter using parallel-connected commutating capacitor units
Assignee: AT&T Inc
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Filing: 1972-07-24
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Granted: 1973-09-11
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Expires: 1992-07-24
Abstract
Abstract Plural commutating capacitor, 2-terminal, impedance units are included in parallel-connected branch circuits which are, in turn, connected in series in a signal path to suppress a predetermined signal frequency as well as certain harmonic frequency-rejection bands that would otherwise be present if a single commutating capacitor unit were employed. The plural units are essentially the same in structure and are driven for commutation switching at the same frequency but in different phases with respect to one another.
Inventors
- 👤 L Bahler
- 👤 J Condon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:29
CPC Classifications
H; H03; H03H; H03H19/00; H03H19/002
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
39 words
In combination, a plurality N of commutating capacitor units, means for connecting said units in parallel signal paths, and means for driving said units in different phases with respect to one another for commutating capacitor connections in such units.
Claim 2
Dependent Claim
39 words
In combination, a plurality N of commutating capacitor units, means for connecting said units in parallel signal paths, and means for driving said units in different phases with respect to one another for commutating capacitor connections in such units.
Claim 3
Dependent Claim
83 words
The combination in accordance with claim 1 in which each of said units comprises, an input connection and an output connection, a plurality of capacitors interconnected with one another in a circuit having a predetermined number, greater than two, of terminals, and means for coupling the terminals of different paired combinations of said terminals to said input and output connections, respectively, in a predetermined recurring sequence of time intervals, each of said combinations including in series therebetween at least two of said capacitors.
Claim 4
Dependent Claim
67 words
A band-rejection filter comprising, a plurality N of commutating capacitor units, each of said units including a plurality of capacitors connectible in recurrent alternating connection cycles, means for connecting said units in parallel-connected branch paths of a signal path in said filter, and means for driving said units in different phases with repsect to one another for commutating capacitor connections in said units through said recurrent cycles.
Claim 5
Dependent Claim
67 words
A band-rejection filter comprising, a plurality N of commutating capacitor units, each of said units including a plurality of capacitors connectible in recurrent alternating connection cycles, means for connecting said units in parallel-connected branch paths of a signal path in said filter, and means for driving said units in different phases with repsect to one another for commutating capacitor connections in said units through said recurrent cycles.
Claim 6
Dependent Claim
40 words
The filter in accordance with claim 3 in which said driving means comprises, means for driving said units in different phases of the same frequency which are 60 degrees/N apart from the phase of every other one of said units.
Claim 7
Dependent Claim
50 words
The filter in accordance with claim 3 in which said driving means comprises, means for fixing said different phases with respect to one another for suppressing all harmonic effects of said filter except those at harmonics satisfying the expression (6*N*I + or - 1) wherein I is any positive integer.
Claim 8
Dependent Claim
56 words
The filter in accordance with claim 3 in which, two of said units are provided, and said driving means drives said units at the same commuTating frequency with thirty degrees difference in phase as measured on the waveform of a signal at the frequency at the center of the fundamental frequency rejection band of said filter.
Claim 9
Dependent Claim
56 words
The filter in accordance with claim 3 in which, three of said units are provided, and said driving means drives said units at the same commutating frequency with twenty degrees difference in phase as measured on the waveform of a signal at the frequency at the center of the fundamental frequency rejection band of said filter.
Claim 10
Dependent Claim
46 words
The filter in accordance with claim 3 in which, said connecting means comprises a plurality N of current limiting resistors, and means for connecting each of said resistors in series with an output of a different one of said units in its respective parallel-connected branch path.
Claim 11
Dependent Claim
41 words
The filter in accordance with claim 3 in which, input and output connections are provided, and said connecting means includes, an operational amplifier, and means for connecting said parallel-connected units and said amplifier in series between said input and output connections.
Claim 12
Dependent Claim
71 words
The filter in accordance with claim 9 in which said amplifier comprises an inverting input connection which is connected in said series signal path to a common terminal of said parallel-connected units which is remote from said input connections, said amplifier also includes a noninverting input connection which is coupled to a reference potential, and a feedback resistor is connected between an output of said amplifier and said inverting input connection.
Claim 13
Dependent Claim
32 words
The filter in accordance with claim 10 in which, said output connections include a terminating resistor connected therebetween, and means for connecting one of said output connections to said reference potential terminal.
Claim 14
Dependent Claim
37 words
The filter in accordance with claim 3 in which said signal path wherein said parallel-connected commutating capacitor units are connected is a series signal path connecting an input terminal of said filter with its corresponding output terminal.
Claim 15
Dependent Claim
76 words
The combination in accordance with claim 1 in which each of said units comprises, a plurality of capacitors interconnected with one another, and means for commutating said interconnected capacitors through a predetermined sequence of connection combinations between input and output connections of said unit, each of said combinations including a plurality of capacitors connected between said input and output connections and each such capacitor being included in at least two of said combinations in said sequence.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-10 | 1977-03-12 | 1977-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-10 | 1981-03-12 | 1981-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-10 | 1985-03-12 | 1985-09-11 | $7700.00 | Window Closed / Lapsed |