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US5020102A
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US
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Semi-floating AC/DC active termination circuit with current sink
Assignee: Rockwell Firstpoint Contact Corp
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Filing: 1989-08-01
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Granted: 1991-05-28
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Expires: 2009-08-01
Abstract
Abstract A semi-floating AC/DC active termination circuit with current sink. A voice frequency transmission line termination circuit has at least tip and ring terminals and provides an AC termination impedance and a DC termination resistance. The circuit has at least a first resistance element connected between the tip and ring terminate which forms the DC termination resistance. A first resistor/capacitor series circuit, having at least a resistor and capacitor connected in series, is connected between the tip terminals and a first virtual ground terminal, and a second resistor/capacitor series circuit, having at least a resistor and capacitor connected in series, is connected between the ring terminal and a second virtual ground terminal. The first resistance element and the first and second resistor/capacitor series circuits form the AC termination impedance. A first operational amplifier has an output connected to the first virtual ground terminal and a second operational amplifier has an output connected to the second virtual ground terminal. The first and second operational amplifiers provide a virtual ground for voltages and currents appearing at the tip and ring terminals. In a preferred embodiment the first operational amplifier has a negative input operationally connected to a voltage source and has a positive input connected to a signal receiving line. The second operational amplifier has a negative input operationally connected to the signal receiving line and has a positive input connected to a circuit ground.
Inventors
- 👤 Ian A. Schorr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:34
CPC Classifications
H; H04; H04M; H04M19/00; H04M19/001; H04M19/005; H04M3/00; H04M3/005
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
87 words
A transmission line termination circuit having at least tip and ring terminals and providing an AC termination impedance and a DC termination resistance comprising: at least a first resistance element connected between the tip and ring terminals; a first resistor and capacitor series circuit connected between the tip terminal and virtual ground; a second resistor and capacitor series circuit connected between the ring terminal and virtual ground; a first resistance element being the DC termination resistance and the resistance element floating with respect to the virtual ground.
Claim 2
Dependent Claim
87 words
A transmission line termination circuit having at least tip and ring terminals and providing an AC termination impedance and a DC termination resistance comprising: at least a first resistance element connected between the tip and ring terminals; a first resistor and capacitor series circuit connected between the tip terminal and virtual ground; a second resistor and capacitor series circuit connected between the ring terminal and virtual ground; a first resistance element being the DC termination resistance and the resistance element floating with respect to the virtual ground.
Claim 3
Dependent Claim
26 words
The circuit described in claim 1, wherein the first resistance element and the first and second resistor and capacitor series circuits form the AC termination impedance.
Claim 4
Dependent Claim
34 words
The circuit described in claim 2, wherein the first resistance element is the DC termination resistance and wherein the DC termination resistance is larger than an AC termination resistance of the AC termination impedance.
Claim 5
Dependent Claim
23 words
The circuit described in claim 1, wherein each of the first and second resistor and capacitor series circuits has substantially the same impedance.
Claim 6
Dependent Claim
53 words
The circuit described in claim 1, wherein the first resistance element is the DC termination resistance and wherein the DC termination resistance is substantially smaller than a resistance portion of an equivalent impedance of the resistor in series with the capacitor in either of said first and second resistor and capacitor series circuits.
Claim 7
Dependent Claim
30 words
The circuit described in claim 2, wherein the first resistance element is the DC termination resistance and forms a substantial part of the resistance portion of the AC termination impedance.
Claim 8
Dependent Claim
97 words
A transmission line termination circuit having at least tip and ring terminals and providing an AC termination impedance and a DC termination resistance comprising: at least a first resistance element connected between the tip and ring terminals; a first resistor and capacitor series circuit connected between the tip terminal and virtual ground; and a second resistor and capacitor series circuit connected between the ring terminal and virtual ground; the first resistance element being the DC termination resistance, and the first resistance element and the first and second resistor and capacitor series circuits forming the AC termination impedance.
Claim 9
Dependent Claim
97 words
A transmission line termination circuit having at least tip and ring terminals and providing an AC termination impedance and a DC termination resistance comprising: at least a first resistance element connected between the tip and ring terminals; a first resistor and capacitor series circuit connected between the tip terminal and virtual ground; and a second resistor and capacitor series circuit connected between the ring terminal and virtual ground; the first resistance element being the DC termination resistance, and the first resistance element and the first and second resistor and capacitor series circuits forming the AC termination impedance.
Claim 10
Dependent Claim
18 words
The circuit described in claim 7, wherein the resistance element is floating with respect to the virtual ground.
Claim 11
Dependent Claim
34 words
The circuit described in claim 7, wherein the first resistance element is the DC termination resistance and wherein the DC termination resistance is larger than an AC termination resistance of the AC termination impedance.
Claim 12
Dependent Claim
26 words
The circuit described in claim 7 wherein each of the first and second resistor and capacitor series circuits comprises a resistor in series with a capacitor.
Claim 13
Dependent Claim
23 words
The circuit described in claim 10 wherein each of the first and second resistor and capacitor series circuits has substantially the same impedance.
Claim 14
Dependent Claim
42 words
The circuit described in claim 10, wherein the DC termination resistance is substantially smaller than a resistance portion of an equivalent impedance of the resistor in series with the capacitor in either of said first and second resistor and capacitor series circuits.
Claim 15
Dependent Claim
24 words
The circuit described in claim 7, wherein the first resistance element forms a substantial part of the resistance portion of the AC termination impedance
Claim 16
Dependent Claim
168 words
A transmission line termination circuit having at least tip and ring terminals and providing an AC termination impedance and a DC termination resistance comprising: at least a first resistance element connected between the tip and ring terminals which forms the DC termination resistance; a first resistor and capacitor series circuit, having at least a resistor and capacitor connected in series, connected between the tip terminal and a first virtual ground terminal; a second resistor and capacitor series circuit, having at least a resistor and capacitor connected in series, connected between the ring terminal and a second virtual ground terminal; the first resistance element and the first and second resistor and capacitor series circuits forming the AC termination impedance; a first operational amplifier having an output connected to the first virtual ground terminal; a second operational amplifier having an output connected to the second virtual ground terminal; and the first and second operational amplifiers providing a virtual ground for voltages and currents appearing at the tip and ring terminals.
Claim 17
Dependent Claim
168 words
A transmission line termination circuit having at least tip and ring terminals and providing an AC termination impedance and a DC termination resistance comprising: at least a first resistance element connected between the tip and ring terminals which forms the DC termination resistance; a first resistor and capacitor series circuit, having at least a resistor and capacitor connected in series, connected between the tip terminal and a first virtual ground terminal; a second resistor and capacitor series circuit, having at least a resistor and capacitor connected in series, connected between the ring terminal and a second virtual ground terminal; the first resistance element and the first and second resistor and capacitor series circuits forming the AC termination impedance; a first operational amplifier having an output connected to the first virtual ground terminal; a second operational amplifier having an output connected to the second virtual ground terminal; and the first and second operational amplifiers providing a virtual ground for voltages and currents appearing at the tip and ring terminals.
Claim 18
Dependent Claim
59 words
The circuit described in claim 14, wherein the first operational amplifier has a negative input operationally connected to a voltage source and has a positive input connected to a signal receiving line; and wherein the second operational amplifier has a negative input operationally connected to the signal receiving line and has a positive input connected to a circuit ground.
Claim 19
Dependent Claim
18 words
The circuit described in claim 14, wherein the resistance element is floating with respect to the virtual ground.
Claim 20
Dependent Claim
24 words
The circuit described in claim 14, wherein the DC termination resistance is larger than an equivalent AC termination resistance of the AC termination impedance.
Claim 21
Dependent Claim
23 words
The circuit described in claim 14, wherein each of the first and second resistor and capacitor series circuits has substantially the same impedance.
Claim 22
Dependent Claim
42 words
The circuit described in claim 14, wherein the DC termination resistance is substantially smaller than a resistance portion of an equivalent impedance of the resistor in series with the capacitor in either of said first and second resistor and capacitor series circuits.
Claim 23
Dependent Claim
24 words
The circuit described in claim 14, wherein the DC termination resistance forms a substantial part of the resistance portion of the AC termination impedance.
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) | 1994-05-27 | 1994-11-26 | 1995-05-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-05-27 | 1998-11-26 | 1999-05-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-05-27 | 2002-11-26 | 2003-05-28 | $7700.00 | Window Closed / Lapsed |