US4015224A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Active band-pass filter
Assignee: THIELSCHER ELECTRONIC GERHARD THIELSCHER
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Filing: 1975-07-31
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Granted: 1977-03-29
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Expires: 1995-07-31
Abstract
Abstract An active band-pass filter comprises at least one unit consisting of two filter sections connected in tandem via capacitive coupling impedances, each section including an operational amplifier with an R/C network in its feedback path. The network has two parallel branches, one of them being divided into two series capacitances whose junction is grounded through a shunt resistance and is also connected to the output of the other section through one of the coupling capacitances acting as a feedback impedance. One of these series capacitances, lying between that junction and the inverting input of the operational amplifier, is also in series with an input impedance which in the case of the first section is a high-ohmic resistor and in the case of the second section is the other coupling capacitance. In a modified unit, constituting the dual of the first one, all the capacitances of the former are replaced by resistances and vice versa.
Inventors
- 👤 Hans Benzinger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:53
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/126; H03H11/1217
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
184 words
An active band-pass filter comprising at least one unit formed from a first and second filter section in tandem, each of said sections including an operational amplifier with an inverting input, a common terminal and an output, said operational amplifier being provided with a resistive/capacitive feedback network having two parallel impedance branches connected between said output and said inverting input, one of said branches being divided into two series impedances of a first type forming a junction therebetween, the other of said branches being an impedance of a second type, one of said types being resistive, the other of said types being capacitive, each of said sections further including a shunt impedance of said second type connected between said junction and said common terminal; an input impedance of said second type connected to said junction of said first section; a coupling impedance of said first type connected between said output of said first section and said junction of said second section; and a feedback impedance of said first type connected between said output of said second section and said junction of said first section.
Claim 2
Dependent Claim
184 words
An active band-pass filter comprising at least one unit formed from a first and second filter section in tandem, each of said sections including an operational amplifier with an inverting input, a common terminal and an output, said operational amplifier being provided with a resistive/capacitive feedback network having two parallel impedance branches connected between said output and said inverting input, one of said branches being divided into two series impedances of a first type forming a junction therebetween, the other of said branches being an impedance of a second type, one of said types being resistive, the other of said types being capacitive, each of said sections further including a shunt impedance of said second type connected between said junction and said common terminal; an input impedance of said second type connected to said junction of said first section; a coupling impedance of said first type connected between said output of said first section and said junction of said second section; and a feedback impedance of said first type connected between said output of said second section and said junction of said first section.
Claim 3
Dependent Claim
18 words
A band-pass filter as defined in claim 1 wherein said series impedances are of substantially the same magnitude.
Claim 4
Dependent Claim
43 words
A band-pass filter as defined in claim 2 wherein the magnitude of said series impedances is substantially the same in said first and second sections, the magnitude of said shunt impedance in said second section being substantially less than in said first section.
Claim 5
Dependent Claim
36 words
A band-pass filter as defined in claim 3 wherein said input impedance, said shunt impedance and the impedance of said other of said branches are resistive, said series impedances, coupling impedance and feedback impedance being capactive.
Claim 6
Dependent Claim
21 words
A band-pass filter as defined in claim 4 wherein said feedback impedance has a substantially lower capacitance than said coupling impedance.
Claim 7
Dependent Claim
30 words
A band-pass filter as defined in claim 4 wherein said input impedance has a substantially higher resistance than said shunt impedance and the impedance of said other of said branches.
Claim 8
Dependent Claim
14 words
A band-pass filter comprising a plurality of cascaded units as defined in claim 1.
Claim 9
Dependent Claim
30 words
A band-pass filter as defined in claim 7 wherein the impedance of said first type are capacitive in one of said cascaded units and in another of said cascaded units.
References Cited (Backward Citations)
US3375451A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-03-28 | 1980-09-27 | 1981-03-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-03-28 | 1984-09-27 | 1985-03-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-03-28 | 1988-09-27 | 1989-03-29 | $7700.00 | Window Closed / Lapsed |