Push pull line driver circuit

Claim 2

A line driver circuit comprising a current switch including an input adapted to receive an electrical digital signal at either one of two potential levels, and a pair of outputs for transmitting respective electrical digital signals of mutually opposite phase so that the signal transmitted by one output is at one potential level and the signal transmitted by the other output is at another potential level, a single-ended push-pull output stage including a pair of inputs, an output, and means responsive to an electrical signal at an upper potential level at one of said output stage inputs and to an electrical signal at a lower potential level at the other of said output stage inputs for causing the potential of said output stage output to swing downwardly, and responsive to an electrical signal at a lower potential level at said one output stage input and to an electrical signal at an upper potential level at said other output stage input for causing the potential of said output stage output to swing upwardly, first means direct-current coupling one of said current switch outputs to a first of said output stage inputs, and second means direct-current coupling the other of said current switch outputs to a second of said output stage inputs, means for limiting the amplitude of the downward swing of the output stage output potential, an active feedback network having one end connected to said output stage output and another end connected to one of said current switch outputs.

Claim 3

A line driver circuit as set forth in claim 1 wherein said feedback network comprises a feedback transistor having a collector and an emitter, meaNs connecting said feedback transistor emitter to said output stage output, and means connecting said feedback transistor collector to said one output of said current switch.

Claim 4

A line driver circuit comprising a current switch including an input adapted to receive an electrical digital signal at either one of two potential levels, and a pair of outputs for transmitting respective electrical digital signals of mutually opposite phase so that the signal transmitted by one output is at one potential level and the signal transmitted by the other output is at another potential level, a single-ended push-pull output stage including a pair of inputs, an output, and means responsive to an electrical signal at an upper potential level at one of said output stage inputs and to an electrical signal at a lower potential level at the other of said output stage inputs for causing the potential of said output stage output to swing downwardly, and responsive to an electrical signal at a lower potential level at said one output stage input and to an electrical signal at an upper potential level at said other output stage input for causing the potential of said output stage output to swing upwardly, first means direct-current coupling one of said current switch outputs to a first of said output stage inputs, and second means direct-current coupling the other of said current switch outputs to a second of said output stage inputs, a pair of transistors each having a collector, a base, and an emitter, a current source connected to said emitters, said current switch input being connected to one of said bases, and bias means connected to the other of said bases, one of said collectors being connected to one of said current switch outputs, the other of said collectors being connected to the other of said current switch outputs, a pair of load transistors of a conductivity type opposite to that of said current switch transistors, each of said load transistors having a collector connected to a collector of a respective one of said current switch transistors.

Claim 5

A line driver circuit comprising a current switch including an input adapted to receive an electrical digital signal at either one of two potential levels, and a pair of outputs for transmitting respective electrical digital signals of mutually opposite phase so that the signal transmitted by one output is at one potential level and the signal transmitted by the other output is at another potential level, a single-ended push-pull output stage including a pair of inputs, an output, and means responsive to an electrical signal at an upper potential level at one of said output stage inputs and to an electrical signal at a lower potential level at the other of said output stage inputs for causing the potential of said output stage output to swing downwardly, and responsive to an electrical signal at a lower potential level at said one output stage input and to an electrical signal at an upper potential level at said other output stage input for causing the potential of said output stage output to swing upwardly, first means direct-current coupling one of said current switch outputs to a first of said output stage inputs, and second means direct-current coupling the other of said current switch outputs to a second of said output stage inputs, a pair of transistors each having a collector, a base, and an emitter, a current source connected to said emitters, said current switch input being connected to one of said bases, and bias means connected to the other of said bases, one of said collectors being connected to one of said current switch outputs, the other of said collectors being connected to the other of said current switch outputs, a pair of load transistors of a conductivity type opposite to that of said current switch transistors, each of said load transistors having a collector connected to a collector of a respective one of said current switch transistors.

Claim 6

A line driver circuit comprising a current switch including an input adapted to receive an electrical digital signal at either one of two potential levels, and a pair of outputs for transmitting respective electrical digital signals of mutually opposite phase so that the signal transmitted by one output is at one potential level and the signal transmitted by the other output is at another potential level, a single-ended push-pull output stage including a pair of inputs, an output, and means responsive to an electrical signal at an upper potential level at one of said output stage inputs and to an electrical signal at a lower potential level at the other of said output stage inputs for causing the potential of said output stage output to swing downwardly, and responsive to an electrical signal at a lower potential level at said one output stage input and to an electrical signal at an upper potential level at said other output stage input for causing the potential of said output stage output to swing upwardly, first means direct-current coupling one of said current switch outputs to a first of said output stage inputs, and second means direct-current coupling the other of said current switch outputs to a second of said output stage inputs, a pair of transistors each having a collector, a base, and an emitter, a current source connected to said emitters, said current switch input being connected to one of said bases, and bias means connected to the other of said bases, one of said collectors being connected to one of said current switch outputs, the other of said collectors being connected to the other of said current switch outputs, means for limiting the amplitude of the downward swing of the output stage output potential, an active feedback network having one end cOnnected to said output stage output and another end connected to one of said current switch outputs.

Claim 7

A line driver circuit comprising a current switch including an input adapted to receive an electrical digital signal at either one of two potential levels, and a pair of outputs for transmitting respective electrical digital signals of mutually opposite phase so that the signal transmitted by one output is at one potential level and the signal transmitted by the other output is at another potential level, a single-ended push-pull output stage including a pair of inputs, an output, and means responsive to an electrical signal at an upper potential level at one of said output stage inputs and to an electrical signal at a lower potential level at the other of said output stage inputs for causing the potential of said output stage output to swing downwardly, and responsive to an electrical signal at a lower potential level at said one output stage input and to an electrical signal at an upper potential level at said other output stage input for causing the potential of said output stage output to swing upwardly, first means direct-current coupling one of said current switch outputs to a first of said output stage inputs, and second means direct-current coupling the other of said current switch outputs to a second of said output stage inputs, a pair of transistors each having a collector, a base, and an emitter, a current source connected to said emitters, said current switch input being connected to one of said bases, and bias means connected to the other of said bases, one of said collectors being connected to one of said current switch outputs, the other of said collectors being connected to the other of said current switch outputs, means for limiting the amplitude of the downward swing of the output stage output potential, an active feedback network having one end cOnnected to said output stage output and another end connected to one of said current switch outputs.

Claim 8

A line driver circuit as set forth in claim 4 wherein said feedback network comprises a feedback transistor having a collector and an emitter, means connecting said feedback transistor emitter to said output stage output, and means connecting said feedback transistor collector to said one output of said current switch.

Claim 9

A line driver circuit comprising a current switch including an input adapted to receive an electrical digital signal at either one of two potential levels, and a pair of outputs for transmitting respective electrical digital signals of mutually opposite phase so that the signal transmitted by one output is at one potential level and the signal transmitted by the other output is at another potential level, a single-ended push-pull output stage including a pair of inputs, an output, and means responsive to an electrical signal at an upper potential level at one of said output stage inputs and to an electrical signal at a lower potential level at the other of said output stage inputs for causing the potential of said output stage output to swing downwardly, and responsive to an electrical signal at a lower potential level at said one output stage input and to an electrical signal at an upper potential level at said other output stage input for causing the potential of said output stage output to swing upwardly, first means direct-current coupling one of said current switch outputs to a first of said output stage inputs, and second means direct-current coupling the other of said current switch outputs to a second of said output stage inputs, a pair of transistors each having a collector, a base, and an emitter, a current source connected to said emitters, said current switch input being connected to one of said bases, and bias means connected to the other of said bases, one of said collectors being connected to one of said current switch outputs, the other ofsaid collectors being connected to the other of said current switch outputs, a pair of load transistors of a conductivity type opposite to that of said current switch transistors, each of of said load transistors having a collector connected to a collector of a respective one of said current switch transistors.

Claim 10

A line driver circuit comprising a current switch including an input adapted to receive an electrical digital signal at either one of two potential levels, and a pair of outputs for transmitting respective electrical digital signals of mutually opposite phase so that the signal transmitted by one output is at one potential level and the signal transmitted by the other output is at another potential level, a single-ended push-pull output stage including a pair of inputs, an output, and means responsive to an electrical signal at an upper potential level at one of said output stage inputs and to an electrical signal at a lower potential level at the other of said output stage inputs for causing the potential of said output stage output to swing downwardly, and responsive to an electrical signal at a lower potential level at said one output stage input and to an electrical signal at an upper potential level at said other output stage input for causing the potential of said output stage output to swing upwardly, first means direct-current coupling one of said current switch outputs to a first of said output stage inputs, and second means direct-current coupling the other of said current switch outputs to a second of said output stage inputs, a pair of transistors each having a collector, a base, and an emitter, a current source connected to said emitters, said current switch input being connected to one of said bases, and bias means connected to the other of said bases, one of said collectors being connected to one of said current switch outputs, the other ofsaid collectors being connected to the other of said current switch outputs, a pair of load transistors of a conductivity type opposite to that of said current switch transistors, each of of said load transistors having a collector connected to a collector of a respective one of said current switch transistors.

Claim 11

A line driver circuit comprising a current switch including an input adapted to receive an electrical digital signal at either one of two potential levels, and a pair of outputs for transmitting respective electrical digital signals of mutually opposite phase so that the signal transmitted by one output is at one potential level and the signal transmitted by the other output is at another potential level, a single-ended push-pull output stage including a pair of inputs, an output, and means responsive to an electrical signal at an upper potential level at one of said output stage inputs and to an electrical signal at a lower potential level at the other of said output stage inputs for causing the potential of said output stage output to swing downwardly, and responsive to an electrical signal at a lower potential level at said one output stage input and to an electrical signal at an upper potential level at said other output stage input for causing the potential of said output stage output to swing upwardly, first means direct-current coupling one of said current switch outputs to a first of said output stage inputs, and second means direct-current coupling the other of said current switch outputs to a second of said output stage inputs, a pair of output transistors each having a collector, a base and an emitter, one of said output stage inputs being connected to one of said bases, the other of said output stage inputs being connected to the other of said bases, a power supply having two supply terminals, one of said output transistors having its collector connected to one of said supply terminals, the other of said output transistors having its emitter connected to the other supply terminals, and means connecting the emitter of said one output transistor and the collector of said other output transistor to said output stage output, means for limiting the amplitude of the downward swing of the output stage output potential, and an active feedback network having one end connected to said output stage output and another end connected to one of said current switch outputs.

Claim 12

A line driver circuit comprising a current switch including an input adapted to receive an electrical digital signal at either one of two potential levels, and a pair of outputs for transmitting respective electrical digital signals of mutually opposite phase so that the signal transmitted by one output is at one potential level and the signal transmitted by the other output is at another potential level, a single-ended push-pull output stage including a pair of inputs, an output, and means responsive to an electrical signal at an upper potential level at one of said output stage inputs and to an electrical signal at a lower potential level at the other of said output stage inputs for causing the potential of said output stage output to swing downwardly, and responsive to an electrical signal at a lower potential level at said one output stage input and to an electrical signal at an upper potential level at said other output stage input for causing the potential of said output stage output to swing upwardly, first means direct-current coupling one of said current switch outputs to a first of said output stage inputs, and second means direct-current coupling the other of said current switch outputs to a second of said output stage inputs, a pair of output transistors each having a collector, a base and an emitter, one of said output stage inputs being connected to one of said bases, the other of said output stage inputs being connected to the other of said bases, a power supply having two supply terminals, one of said output transistors having its collector connected to one of said supply terminals, the other of said output transistors having its emitter connected to the other supply terminals, and means connecting the emitter of said one output transistor and the collector of said other output transistor to said output stage output, means for limiting the amplitude of the downward swing of the output stage output potential, and an active feedback network having one end connected to said output stage output and another end connected to one of said current switch outputs.

Claim 13

A line driver circuit as set forth in claim 7 wherein said feedback network comprises a feedback transistor having a collector and an emitter, means connecting said feedback transistor emitter to said output stage output, and means connecting said feedback transistor collector to said one output of said current switch.

Claim 14

A line driver circuit comprising a current switch including an input adapted to receive an electrical digital signal at either one of two potential levels, and a pair of outputs for transmitting respective electrical digital signals of mutually opposite phase so that the signal transmitted by one output is at one potential level and the signal transmitted by the other output is at another potential level, a single-ended push-pull output stage including a pair of inputs, an output, first means direct-current coupling one of said current switch outputs to a first of said output stage inputs, and second means direct-current coupling the other of said current switch outputs to a second of said output stage inputs, said current switch comprising a pair of transistors each having a collector, a base, and an emitter, a current source connected to said emitters, said current switch input being connected to one of said bases, and bias means connected to the other of said bases, one of said collectors being connected to one of said current switch outputs, the other of said collectors being connected to the other of said current switch outputs, said output stage comprising a pair of output transistors each having a collector, a base and an emitter, one of said output stage inputs being connected to one of said bases, the other of said output stage inputs being connected to the other of said bases, a power supply having two supply terminals, one of said output transistors having its collector connected to one of said supply terminals, the other of said output transistors having its emitter connected to the other supply terminals, and means connecting the emitter of said one output transistor and the collector of said other output transistor to said output stage output, and a digital signal source having an output connected to said current switch input to transmit thereto said electrical digital signal at either one of two potential levels, a pair of load transistors of a conductivity type opposite to that of said current switch transistors, each of said load transistors hacing a collector connected to a collector of a respective one of said current switch transistors.

Claim 15

A line driver circuit comprising a current switch including an input adapted to receive an electrical digital signal at either one of two potential levels, and a pair of outputs for transmitting respective electrical digital signals of mutually opposite phase so that the signal transmitted by one output is at one potential level and the signal transmitted by the other output is at another potential level, a single-ended push-pull output stage including a pair of inputs, an output, first means direct-current coupling one of said current switch outputs to a first of said output stage inputs, and second means direct-current coupling the other of said current switch outputs to a second of said output stage inputs, said current switch comprising a pair of transistors each having a collector, a base, and an emitter, a current source connected to said emitters, said current switch input being connected to one of said bases, and bias means connected to the other of said bases, one of said collectors being connected to one of said current switch outputs, the other of said collectors being connected to the other of said current switch outputs, said output stage comprising a pair of output transistors each having a collector, a base and an emitter, one of said output stage inputs being connected to one of said bases, the other of said output stage inputs being connected to the other of said bases, a power supply having two supply terminals, one of said output transistors having its collector connected to one of said supply terminals, the other of said output transistors having its emitter connected to the other supply terminals, and means connecting the emitter of said one output transistor and the collector of said other output transistor to said output stage output, and a digital signal source having an output connected to said current switch input to transmit thereto said electrical digital signal at either one of two potential levels, a pair of load transistors of a conductivity type opposite to that of said current switch transistors, each of said load transistors hacing a collector connected to a collector of a respective one of said current switch transistors.

Claim 16

A line driver circuit as set forth in claim 9 and comprising means for limiting the amplitude of the downward swing of the output stage output potential.

Claim 17

A line driver circuit as set forth in claim 10 wherein said limiting means comprises an active feedback network having one end connected to said output stage output and another end connected to one of said current switch outputs.

Claim 18

A line driver circuit as set forth in claim 11 wherein said feedback network comprises a feedback transistor having a collector and an emitter, means connecting said feedback transistor emitter to said output stage output, and means connecting said feedback transistor collector to said one output of said current switch.

Claim 19

A line driver circuit as set forth in claim 12 and comprising means for limiting the upward swing of said output stage output potential.

Claim 20

A line driver circuit as set forth in claim 13 wherein said last-recited limiting means comprises a clamping diode, a voltage source, means connecting one end of said diode to said voltage source, and means connecting the other end of said diode to one of said current switch outputs.