Electronic subscriber line connection circuit
First Claim
1. A subscriber line connection circuit connected to a transmission circuit and to a reception circuit, connected to one line wire via a first fixed contact, a first moving contact of a ringing relay and a first resistor, and to the other line wire via a second fixed contact, a second moving contact of said ringing relay, and a second resistor, and including a loop state signalling circuit connected to the terminals of the first and second resistors and delivering a loop signal, said transmission circuit being connected via a third resistor to the first resistor and via a fourth resistor to the second resistor, wherein the connection circuit also comprises:
- first and second differential amplifier circuits having their inputs connected to said reception circuit;
a first symmetrical amplifier circuit connected to the output of the first differential amplifier circuit via a fifth resistor and having an output connected to the first resistor;
a second symmetrical amplifier circuit connected to the output of the second differential amplifier circuit via a sixth resistor and having an output connected to the second resistor;
a first feedback circuit connected in parallel with an ensemble constituted by the first symmetrical amplifier circuit and the first resistor;
a second feedback circuit connected in parallel with an ensemble constituted by the second symmetrical amplifier circuit and the second resistor;
a balancing circuit connected to the outputs of the first and second differential amplifier circuit and to a point common to the transmit circuit and the third resistor, and to a second point common to the transmit circuit and the fourth resistor; and
a power supply and filter circuit for filtering the voltage from a battery and for powering the second and first symmetrical amplifier circuits via a power supply series connection, said power supply and filtering circuit being connected to the negative potential of the battery and said first symmetrical amplifier circuit being connected to the positive potential of the battery.
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Accused Products
Abstract
The connection circuit comprises a first differential amplifier circuit having its output connected to a first symmetrical amplifier circuit, a second differential amplifier circuit having its output connected to a second symmetrical amplifier circuit, a power supply and filter circuit for delivering power via a power supply series connection to the two symmetrical amplifier circuits, a balancing circuit, and a loop state signaling circuit. The two differential amplifier circuits are connected firstly to the output of a receive circuit and secondly to ground, and each wire of the line is connected directly via a respective resistor to a transmit circuit. Each symmetrical amplifier circuit is connected to one of the line wires via a contact of a ringing relay and a resistor connected in series. The power supply series connection includes a power supply transistor controlled by a signal indicative of the line being looped.
78 Citations
12 Claims
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1. A subscriber line connection circuit connected to a transmission circuit and to a reception circuit, connected to one line wire via a first fixed contact, a first moving contact of a ringing relay and a first resistor, and to the other line wire via a second fixed contact, a second moving contact of said ringing relay, and a second resistor, and including a loop state signalling circuit connected to the terminals of the first and second resistors and delivering a loop signal, said transmission circuit being connected via a third resistor to the first resistor and via a fourth resistor to the second resistor, wherein the connection circuit also comprises:
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first and second differential amplifier circuits having their inputs connected to said reception circuit; a first symmetrical amplifier circuit connected to the output of the first differential amplifier circuit via a fifth resistor and having an output connected to the first resistor; a second symmetrical amplifier circuit connected to the output of the second differential amplifier circuit via a sixth resistor and having an output connected to the second resistor; a first feedback circuit connected in parallel with an ensemble constituted by the first symmetrical amplifier circuit and the first resistor; a second feedback circuit connected in parallel with an ensemble constituted by the second symmetrical amplifier circuit and the second resistor; a balancing circuit connected to the outputs of the first and second differential amplifier circuit and to a point common to the transmit circuit and the third resistor, and to a second point common to the transmit circuit and the fourth resistor; and a power supply and filter circuit for filtering the voltage from a battery and for powering the second and first symmetrical amplifier circuits via a power supply series connection, said power supply and filtering circuit being connected to the negative potential of the battery and said first symmetrical amplifier circuit being connected to the positive potential of the battery. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification