US4485277A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for transmitting and/or receiving balanced signals on a two-wire telecommunication line
Assignee: Siemens Corp
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Filing: 1982-02-18
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Granted: 1984-11-27
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Expires: 2002-02-18
Abstract
Abstract A transformerless hybrid circuit arrangement for a subscriber line interface circuit of a telecommunications exchange is disclosed. A preferred embodiment of the hybrid arrangement comprises a first and a second operational amplifier plus a differential amplifier connected together in the following manner: The non-inverting input of the first operational amplifier is connected to a first reference voltage and the output of this amplifier is connected (1) via a first resistor to one wire of the two-wire subscriber line, and (2) via a third resistor to the inverting input of the amplifier. The non-inverting input of the second operational amplifier is connected to a second reference voltage and to the receiving branch of the four-wire line of the telecommunications exchange. The output of this second operational amplifier is connected via a second resistor to the other wire of the two-wire subscriber line, via a fourth resistor to the inverting input thereof and via a fifth resistor to the inverting input of the first operational amplifier. Each of the two inputs of the differential amplifier are connected, via respective resistors, to one wire of the two-wire subscriber line and to the output of that operational amplifier which is connected to the other wire of the two-wire subscriber line. The output of the differential amplifier is connected to the transmitting branch of the four-wire line of the exchange.
Inventors
- 👤 Morris L. Minch
- 👤 Theodore W. Wagner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:51
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/38; H04B1/40; H04B1/54; H04B1/58; H04B3/00; H04B3/02; H04B3/03
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
272 words
A transformerless hybrid circuit arrangement for use in a subscriber line interface circuit of a telecommunication exchange for coupling a two-wire subscriber line with the transmitting and receiving branches, respectively, of a four-wire line of the exchange, said circuit arrangement comprising, in combination: (a) a first operational amplifier having an inverting and a non-inverting input and an output, said non-inverting input thereof being connected to a first reference voltage and said output thereof being connected via a first resistor to one wire of said two-wire subscriber line and via a third resistor to the inverting input thereof; (b) a second operational amplifier having an inverting and a non-inverting input and an output, said non-inverting input thereof being connected to a second reference voltage and to the receiving branch of the four-wire line of said exchange and said output thereof being connected via a second resistor to the other wire of said two-wire subscriber line, via a fourth resistor to the inverting input thereof and via a fifth resistor to said inverting input of said first operational amplifier; (c) a first summing stage having four inputs and an output, two inputs thereof each being connected, via a respective circuit path, to a separate wire of said two-wire subscriber line and two other inputs thereof each being connected, via a respective circuit path, to the output of a separate one of said operational amplifiers, and said output of said summing stage being connected to the transmitting branch of the four-wire line of said exchange; and (d) means for preventing incoming signals on said receive branch from appearing as outgoing signals on said transmit branch.
Claim 2
Dependent Claim
272 words
A transformerless hybrid circuit arrangement for use in a subscriber line interface circuit of a telecommunication exchange for coupling a two-wire subscriber line with the transmitting and receiving branches, respectively, of a four-wire line of the exchange, said circuit arrangement comprising, in combination: (a) a first operational amplifier having an inverting and a non-inverting input and an output, said non-inverting input thereof being connected to a first reference voltage and said output thereof being connected via a first resistor to one wire of said two-wire subscriber line and via a third resistor to the inverting input thereof; (b) a second operational amplifier having an inverting and a non-inverting input and an output, said non-inverting input thereof being connected to a second reference voltage and to the receiving branch of the four-wire line of said exchange and said output thereof being connected via a second resistor to the other wire of said two-wire subscriber line, via a fourth resistor to the inverting input thereof and via a fifth resistor to said inverting input of said first operational amplifier; (c) a first summing stage having four inputs and an output, two inputs thereof each being connected, via a respective circuit path, to a separate wire of said two-wire subscriber line and two other inputs thereof each being connected, via a respective circuit path, to the output of a separate one of said operational amplifiers, and said output of said summing stage being connected to the transmitting branch of the four-wire line of said exchange; and (d) means for preventing incoming signals on said receive branch from appearing as outgoing signals on said transmit branch.
Claim 3
Dependent Claim
112 words
The circuit arrangement according to claim 1, further comprising: (d) a first differential amplifier having two inputs and an output, one input thereof being connected with the output of said first summing stage and the other input being connected to a third reference voltage; and (e) a first electronic switch having a control input coupled to the output of said first differential amplifier, the circuit parameters of said amplifier and said switch being selected so that said switch changes its output state when the output signal of said first summing stage reaches said third reference voltage; whereby the output of said switch indicates the loop closure condition of said two-wire subscriber line.
Claim 4
Dependent Claim
89 words
The circuit arrangement according to claim 1, further comprising: (f) threshold means connected to the output of said first summing stage and including means for controlling at least one of said first and second reference voltages, wherein said threshold means changes its output state and alters said at least one reference voltage, when the output signal of the first summing stage exceeds a threshold value, in such manner that the output signals of the two operational amplifiers become more equal, thereby limiting the current in said two-wire subscriber line.
Claim 5
Dependent Claim
138 words
The circuit arrangement according to any one of claims 1 to 3, further comprising: (g) a second summing stage having four inputs and an output, said four inputs thereof being connected to receive the same input voltages as the four inputs of said first summing stage; (h) a second differential amplifier having two inputs and an output, one of said two inputs thereof being connected to the output of said second summing stage and the other of said two inputs thereof being connected to a fourth reference voltage; and (i) a second electronic switch connected to said output of said second differential amplifier, said second electronic switch changing its output state when the output signal of said second summing stage reaches said fourth reference voltage, thereby indicating an assymetry in the current flowing over said two-wire subscriber line.
Claim 6
Dependent Claim
23 words
The circuit arrangement according to claim 4, further comprising a low-pass filter arranged between said second summing stage and said second differential amplifier.
Claim 7
Dependent Claim
16 words
The circuit arrangement according to claim 4, wherein said second summing stage includes a differential amplifier.
Claim 8
Dependent Claim
65 words
The circuit arrangement according to claim 4, wherein the output VC of said second summing stage is proportional to V T +V R -V A -V B , where: V R and V T are the ring and tip lead voltages, respectively, of the two-wire subscriber line, and V A and V B are the output voltages, respectively, of said first and second operational amplifiers.
Claim 9
Dependent Claim
36 words
The circuit arrangement according to claim 3, wherein said threshold means includes means for controlling said first reference voltage, thereby altering said first reference voltage in response to said output signal of said first summing stage.
Claim 10
Dependent Claim
16 words
The circuit arrangement according to claim 1, wherein said first summing stage includes a differential amplifier.
Claim 11
Dependent Claim
65 words
The circuit arrangement according to claim 1, wherein the output VS of said first summing stage is proportinal to V B +V R -V A -V T , where: V R and V T are the ring and tip lead voltages respectively, of the two-wire subscriber line, and V A and V B are the output voltages, respectively, of said first and second operational amplifiers.
Claim 12
Dependent Claim
16 words
The circuit arrangement according to claim 1, wherein said first and second resistors have equal values.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-11-27 | 1988-05-28 | 1988-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-11-27 | 1992-05-28 | 1992-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-11-27 | 1996-05-28 | 1996-11-27 | $7700.00 | Window Closed / Lapsed |