Solid state hybrid circuits

Claim 2

An electronic hybrid for coupling a two-wire signal transmission line to a signal source and to a signal-receiving load in a communication system, said electronic hybrid comprising a two-wire port adapted to be electrically connected to said two-wire line for receiving incoming differential information signals from said line, a signal transmit port adapted to be electrically connected to said signal-receiving load, a signal receive port adapted to be electrically connected to said signal source for receiving signals from said source, means connected intermediate said two-wire port and said transmit port for converting the received incoming differential information signals into first single-ended signals and for applying said single-ended signals to said transmit port for transmission to said signal-receiving load, first and second transistors, means for applying second single-ended signals received at said receive port to said first transistor, means electrically connected to and cooperating with said first and second transistors for converting the second single-ended signals applied to said first transistor into outgoing balanced differential signals each having one signal component on a preselected electrode of said first transistor and the other signal component on a preselected electrode of said second transistor, said preselected electrodes of said first and second transistors being electrically connected to said two-wire port for applying the outgoing differential signal thereto for transmission over said line, and further means electrically connected to said first and second transistors for maintaining a high a.c. output impedance on said preselected electrodes of said transistors.

Claim 3

The electronic hybrid defined in claim 1 wherein said further means comprises constant current source means.

Claim 4

The electronic hybrid defined in claim 1 wherein said transistors are biased by direct current conducted by said transmission line and originating from a d.c. power supply source which is connected to said line.

Claim 5

The electronic hybrid defined in claim 3, including a terminating impedance for said transmission line, said terminating impedance being connected across the terminals of said two-wire port, and the output impedances of said transistors being connected in series with each other in a circuit that is connected in parallel with said terminating impedance.

Claim 6

An electronic hybrid for coupling a two-wire signal transmission line to a signal source and to a signal-receiving load in a communication system having a d.c. power source connected to said line remote from said electronic hybrid for powering said electronic hybrid, said electronic hybrid comprising a two-wire port adapted to be electrically connected to said two-wire line for receiving incoming differential information signals from said line, a signal transmit port adapted to be electrically connected to said signal-receiving load, a signal receive port adapted to be electrically connected to said signal source for receiving signals from said source, means connected intermediate said two-wire port and said transmit port for converting the received incoming differential information signals into first single-ended signals and for applying said single-ended signals to said transmit port for transmission to said signal-receiving load, first and second transistors, means for applying second single-ended signals received at said receive port to said first transistor, further means electrically connected to and cooperating with said first and second transistors for converting the second single-ended signals applied to said first transistor into outgoing balanced differential signals each having one signal component on a preselected electrode of said first transistor and the other signal component on a preselected electrode of said second transistor, said preselected electrodes of said first and second transistors being electrically connected by said two-wire port to separate conductors of the two-wire line for applying the outgoing differential signal thereto for transmission over said line, said further means including a first constant current source electrically connected to said first transistor for supplying biasing current to said first transistor, a second constant current source distinct from said first constant current source and electrically connected to said second transistor for supplying biasing current to said second transistor, said first and second constant current sources being electrically connected by said two-wire port to said line and being powered by the direct current conducted by said line from said d.c. power source.

Claim 7

An electronic hybrid for coupling a two-wire signal transmission line to a signal source and to a signal-receiving load in a communication system having a d.c. power source connected to said line remote from said electronic hybrid for powering said electronic hybrid, said electronic hybrid comprising a two-wire port adapted to be electrically connected to said two-wire line for receiving incoming differential information signals from said line, a signal transmit port adapted to be electrically connected to said signal-receiving load, a signal receive port adapted to be electrically connected to said signal source for receiving signals from said source, means connected intermediate said two-wire port and said transmit port for converting the received incoming differential information signals into first single-ended signals and for applying said single-ended signals to said transmit port for transmission to said signal-receiving load, first and second transistors, means for applying second single-ended signals received at said receive port to said first transistor, further means electrically connected to and cooperating with said first and second transistors for converting the second single-ended signals applied to said first transistor into outgoing balanced differential signals each having one signal component on a preselected electrode of said first transistor and the other signal component on a preselected electrode of said second transistor, said preselected electrodes of said first and second transistors being electrically connected by said two-wire port to separate conductors of the two-wire line for applying the outgoing differential signal thereto for transmission over said line, said further means including a first constant current source electrically connected to said first transistor for supplying biasing current to said first transistor, a second constant current source distinct from said first constant current source and electrically connected to said second transistor for supplying biasing current to said second transistor, said first and second constant current sources being electrically connected by said two-wire port to said line and being powered by the direct current conducted by said line from said d.c. power source.

Claim 8

The electronic hybrid defined in claim 5 wherein said first and second transistors are of the bipolar type, and wherein said pre-selected electrodes are the collectors of said first and second transistors.

Claim 9

The electronic hybrid defined in claim 6 wherein said first constant current source comprises a third transistor, wherein said second constant current source comprises a fourth transistor, and third and fourth transistors being of the bipolar type, said third and fourth transistors being electrically connected to said two-wire port to be biased into conduction by the direct current which is conducted by said transmission line from said d.c. power source, said third transistor having its collector connected to supply base biasing current to said first transistor for driving said first transistor into conduction, and said fourth transistor having its collector connected to supply base biasing current to said second transistor to drive said second transistor into conduction.

Claim 10

The electronic hybrid defined in claim 6 wherein the direct current conducted by said transmission line establishes a supply voltage across the terminals of said two-wire port, and wherein said further means comprises a first circuit connected to said first and second transistors for developing a first voltage which varies as a function of any difference between the collector currents of said first and second transistors, a second circuit connected to said two-wire port for developing a second voltage that varies as a function of said supply voltage, an amplifier electrically connected to said first and second circuits for developing an output voltage that varies as a function of the difference between said first and second voltages, and means coupling the output of said amplifier to the bases of said first and second transistors for varying the collector currents of said first and second transistors as a function of the deviation of said output voltage from a predetermined value.

Claim 11

The electronic hybrid defined in claim 8 wherein said first circuit comprises a resistive voltage divider interconnecting the emitters of said first and second transistors.

Claim 12

The electronic hybrid defined in claim 9 wherein said first voltage is developed at a node in said voltage divider, said node being connected to a common return, one terminal of said receive port and one terminal of said transmit port being connected to said common return.

Claim 13

The electronic hybrid defined in any one of the preceding claims 8-10 wherein said second circuit comprises resistor means connected across the terminals of said two-wire port and defining the terminating impedance for said transmission line.

Claim 14

A terminating electronic hybrid for coupling a two-wire signal transmission line to a signal source and to a signal-receiving load in a communication system in which said transmission line is connected to a d.c. power supply source to conduct the direct current which powers said terminating electronic hybrid, said electronic hybrid comprising a two-wire port adapted to be connected to said line for receiving incoming differential information signals from said line, a signal transmit port adapted to be electrically connected to said signal-receiving load, a signal receive port adapted to be electrically connected to said signal source for receiving signals from said source, means connected intermediate said two-wire port and said transmit port for converting the received incoming differential information signals into first single-ended signals and for applying said single-ended signals to said transmit port for transmission to said signal-receiving load, a circuit connected intermediate said receive port and said two-wire port for converting a single-ended signal received at said receive port into an outgoing differential signal and for applying the outgoing differential signal to said two-wire port for transmission over said transmission line, a portion of said circuit being connected across the terminals of said two-wire port to conduct direct current which is supplied by said line from said d.c. power source, the direct current conducted by said line being effective to develop a d.c. supply voltage across the terminals of said two-wire port to power said circuit, and said circuit including means for maintaining the direct current conducted through said portion of said circuit substantially constant regardless of variations in said d.c. supply voltage within the design limits of said circuit.

Claim 15

A terminating electronic hybrid for coupling a two-wire signal transmission line to a signal source and to a signal-receiving load in a communication system in which said transmission line is connected to a d.c. power supply source to conduct the direct current which powers said terminating electronic hybrid, said electronic hybrid comprising a two-wire port adapted to be connected to said line for receiving incoming differential information signals from said line, a signal transmit port adapted to be electrically connected to said signal-receiving load, a signal receive port adapted to be electrically connected to said signal source for receiving signals from said source, means connected intermediate said two-wire port and said transmit port for converting the received incoming differential information signals into first single-ended signals and for applying said single-ended signals to said transmit port for transmission to said signal-receiving load, a circuit connected intermediate said receive port and said two-wire port for converting a single-ended signal received at said receive port into an outgoing differential signal and for applying the outgoing differential signal to said two-wire port for transmission over said transmission line, a portion of said circuit being connected across the terminals of said two-wire port to conduct direct current which is supplied by said line from said d.c. power source, the direct current conducted by said line being effective to develop a d.c. supply voltage across the terminals of said two-wire port to power said circuit, and said circuit including means for maintaining the direct current conducted through said portion of said circuit substantially constant regardless of variations in said d.c. supply voltage within the design limits of said circuit.

Claim 16

The terminating electronic hybrid defined in claim 12 wherein said means in said circuit comprises constant current source means.