Electronic subscriber line connection circuit

• US 5,097,503 A
• Filed: 01/29/1990
• Issued: 03/17/1992
• Est. Priority Date: 01/31/1989
• Status: Expired due to Term

• Current Assignee: Alcatel-Lucent France, SA (Nokia Corporation)
• Original Assignee: Alcatel-Lucent France, SA (Nokia Corporation)
• Inventors: Cotty, Joel
• Primary Examiner(s): Dwyer, James L.
• Assistant Examiner(s): Augustus, Jhancy
• Application Number:
  US07/471,350
• Time in Patent Office: 778 Days
• Field of Search: 379/399, 379/398, 379/400, 379/401, 379/402, 379/403, 379/404, 379/405, 379/387
• US Class Current: 379/399.01
• CPC Class Codes: H04M 19/005 Feeding arrangements without the use of line transformers

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.

Claims

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.

2. A connection circuit according to claim 1, wherein the power supply series connection is constituted by a first power supply zener diode, a seventh resistor, a power supply transistor, and a second power supply zener diode, the first power supply zener diode having its cathode connected to the positive potential and its anode connected to a seventh resistor, the second power supply zener diode having its anode connected to the power supply and filter circuit and its cathode connected to the power supply transistor, and the power supply transistor having its base connected to the positive potential via a protective zener diode, said base receiving a signal B1 for switching on the power supply transistor when the subscriber loop is looped.

3. A connection circuit according to claim 2, wherein the loop state signalling circuit has its output connected to a control transistor having its collector connected firstly to the base of the power supply transistor and secondly to the negative battery potential via a collector resistor, said control transistor delivering said signal B1.

4. A connection circuit according to claim 2, wherein the first symmetrical amplifier circuit comprises the first power supply zener diode, a first amplifier having a positive input connected firstly to the first differential amplifier circuit via the fifth resistor and secondly to the first feedback circuit, a negative input connected to the first fixed contact, a first transistor having its emitter connected to said first fixed contact, its collector connected to the positive battery potential, and its base connected via an eighth resistor to the output from the first amplifier, and a protective zener diode in parallel with the first transistor, the first amplifier having its power supply terminals connected in parallel with the first power supply zener diode.

5. A connection circuit according to claim 2, wherein the second symmetrical amplifier circuit comprises the second power supply zener diode, a second amplifier having a positive input connected firstly to the second differential amplifier circuit via the sixth resistor and secondly to the second feedback circuit, a negative input connected via a ninth resistor to the second fixed contact, and a second transistor having its emitter connected to the second fixed contact, its base connected via a tenth resistor to the output from the second amplifier, and its collector connected via the power supply and filter circuit to the negative battery potential, the second amplifier having its power supply terminal connected in parallel with the second power supply zener diode.

6. A connection circuit according to claim 2, wherein the power supply and filter circuit comprises a third transistor having its emitter connected via an eleventh resistor to the negative potential, and a fourth transistor having its collector connected to the negative potential, its emitter connected to the power supply series connection, and its base connected to its emitter via a first diode, to the positive potential via a filter capacitor, and to the collector of the third transistor, that the emitter of the fourth transistor is connected via a twelfth resistor in series with a second, a third, and a fourth diode to the negative potential, and that the third transistor has its base connected via a thirteenth resistor to a first capacitor itself connected in parallel with the third and fourth diodes.

7. A connection circuit according to claim 2, wherein the first differential amplifier circuit comprises a third amplifier having a positive input connected via a fourtheenth resistor in series with a second capacitor to the output from the reception circuit and via a fifteenth resistor firstly to the anode of the first power supply zener diode via a sixteenth resistor and secondly to the positive potential via a seventeenth resistor, and a negative input connected firstly to its output via an eighteenth resistor and secondly to ground via a nineteenth resistor in series with a third capacitor, said third amplifier having power supply terminals connected in parallel with the first power supply zener diode.

8. A connection circuit according to claim 2, wherein the second differential amplifier circuit comprises a divider bridge constituted by a twentieth resistor and a twenty-first resistor connected in series, said divider bridge being connected in parallel with the second power supply zener diode, and a fourth amplifier having a negative input connected firstly to its output via a twenty-second resistor and secondly to the output of the reception circuit via a twenty-third resistor in series with a fourth capacitor, and a positive input connected firstly to said divider bridge via a twenty-fourth resistor and secondly to ground via a twenty-fifth resistor in series with a fifth capacitor, said fourth amplifier having its power supply terminals connected in parallel with the second power supply zener diode.

9. A connection circuit according to claim 1, wherein the first and second feedback circuits are each constituted by a resistor connected in series with a capacitor.

10. A connection circuit according to claim 1, wherein the second fixed contact of the ringing relay is connected firstly to the positive potential via a fifth diode and secondly to the negative potential via a sixth diode.

11. A connection circuit according to claim 1, wherein the transmit circuit includes sixth and seventh input capacitors with the sixth capacitor being connected to the third resistor and with the seventh capacitor being connected to the fourth resistor.

12. A connection circuit according to claim 1, wherein the balancing circuit comprises a twenty-sixth resistor connected between the output of the first differential amplifier circuit and said first common point, and a twenty-seventh resistor connected between the output of the second differential amplifier circuit and said second common point.