Telephone wire pair compensator utilizing negative capacitance circuit

Claim 2

A balanced negative capacitance element for compensating a telephone wire pair, said element comprising: a first input transistor of a first conductivity type; a first output transistor of a second conductivity type which is complementary to said first type, said first input transistor and said first output transistor forming a first transistor pair; means connecting the collector of said first input transistor to the base of said first output transistor; resistance means for providing negative in-phase feedback around said first transistor pair; means including a first capacitor for providing positive capacitive feedback around said first transistor pair; a second input transistor, said second input transistor being of said second conductivity type; a second output transistor, said second output transistor being of said first conductivity type, said second input transistor and said second output transistor forming a second transistor pair; means connecting the collector of said second input transistor to the base of said second output transistor; resistance means for providing negative in-phase feedback around said second transistor pair; means including a second capacitor for providing positive capacitive feedback around said second transistor pair; circuit means for connecting said first and second output transistors in series across a DC potential source; and means for connecting each of the wires in said telephone pair to one of said input transistors.

Claim 3

A balanced negative capacitance element for compensating a telephone wire pair, said element comprising: a first input transistor of a first conductivity type; a first output transistor of a second conductivity type which is complementary to said first type, said first input transistor and said first output transistor forming a first transistor pair; means connecting the collector of said first input transistor to the base of said first output transistor; means including a first resistance connecting the collector of said first output transistor to the emitter of said first input transistor thereby to provide negative in-phase feedback around said first transistor pair; means including a first capacitor connecting the collector of said first output transistor to the base of said first input transistor thereby to provide positive capacitive feedback around said first transistor pair; a second input transistor, said second input transistor being of said second conductivity type; a second output transistor, said second output transistor being of said first conductivity type, said second input transistor and said second output transistor forming a second transistor pair; means connecting the collector of said second input transistor to the base of said second output transistor; means including a second resistance connecting the collector of said second output transistor to the emitter of said second input transistor thereby to provide negative in-phase feedback around said second transistor pair; means including a second capacitor connecting the collector of said second output transistor to the base of said second input transistor thereby to provide positive capaCitive feedback around said second transistor pair; circuit means for connecting said first and second output transistors in series across a DC potential source, said first and second output transistor being connected collector to collector through a third resistance which is in series with said first and second resistances; and means for connecting each of the wires in said telephone pair to the base of a respective one of said input transistors.

Claim 4

A balanced negative capacitance element for compensating a telephone wire pair, said element comprising: a first input transistor of a first conductivity type; a first output transistor of a second conductivity type which is complementary to said first type, said first input transistor and said first output transistor forming a first transistor pair; means connecting the collector of said first input transistor to the base of said first output transistor; means including a first resistance connecting the collector of said first output transistor to the emitter of said first input transistor thereby to provide negative in-phase feedback around said first transistor pair; means including a first capacitor connecting the collector of said first output transistor to the base of said first input transistor thereby to provide positive capacitive feedback around said first transistor pair; a second input transistor, said second input transistor being of said second conductivity type; a second output transistor, said second output transistor being of said first conductivity type, said second input transistor and said second output transistor forming a second transistor pair; means connecting the collector of said second input transistor to the base of said second output transistor; means including a second resistance connecting the collector of said second output transistor to the emitter of said second input transistor thereby to provide negative in-phase feedback around said second transistor pair; means including a second capacitor connecting the collector of said second output transistor to the base of said second input transistor thereby to provide positive capaCitive feedback around said second transistor pair; circuit means for connecting said first and second output transistors in series across a DC potential source, said first and second output transistor being connected collector to collector through a third resistance which is in series with said first and second resistances; and means for connecting each of the wires in said telephone pair to the base of a respective one of said input transistors.

Claim 5

A negative capacitance element as set forth in claim 2 wherein said first and second input transistors are of the NPN and PNP conductivity types respectively and wherein said first and second output transistors are of the PNP and NPN conductivity types respectively.

Claim 6

A negative capacitance element as set forth in claim 3 wherein each of said transistor pairs is provided with an input terminal which is connected to the base of the respective input transistor through a blocking capacitor and wherein said capacitive feedback capacitors are connected to said input terminals.

Claim 7

A negative capacitance element as set forth in claim 2 including diode means for limiting voltages at the base terminals of said input transistors.

Claim 8

A negative capacitance element as set forth in claim 2 including diode means for limiting voltages at the collector terminals of said output transistors.

Claim 9

A negative capacitance element as set forth in claim 2 including a voltage divider connected across said voltage source and to the base terminals of said input transistors for forward biasing each of said transistor pairs and thereby dividing the voltage provided by said source among said first, second, and third resistances.

Claim 10

In a telephone system including a hybrid and switching means for connecting any one of a plurality of wire pairs to the input terminals of the hybrid, said wire pairs having different shunt capacitances, a compensating system comprising a plurality of capacitors connected across the pairs having the lower shunt capacitances and at least one negative capacitance element connected across a pair having a higher shunt capacitance.

Claim 11

In a telephone system including a hybrid and switching means for connecting any one of a plurality of wire pairs to the input terminals of the hybrid, said wire pairs having different shunt capacitances, a compensating system comprising a plurality of capacitors connected across the pairs having the lower shunt capacitances and at least one negative capacitance element connected across a pair having a higher shunt capacitance.

Claim 12

A compensating system as set forth in claim 8 wherein said negative capacitance element includes: a first input transistor of a first conductivity type; a first output transistor of a second conductivity type which is complementary to said first type, said first input transistor and said first output transistor forming a first transistor pair; means connecting the collector of said first input transistor to the base of said first output transistor; means including a first resistance connecting the collector of said first output transistor to the emitter of said first input transistor thereby to provide negative in-phase feedback around said first transistor pair; means including a first capacitor connecting the collector of said first output transistor to the base of said first input transistor thereby to provide positive capacitive feedback around said first transistor pair; a second input transistor, said second input transistor being of said second conductivity type; a second output transistor, said second output transistor being of said first conductivity type, said second input transistor and said second output transistor forming a second transistor pair; means connecting the collector of said second input transistor to the base of said second output transistor; means including a second resistance connecting the collector of said second output transistor to the emitter of said second input transistor thereby to provide negative in-phase feedback around said second transistor pair; means including a second capacitor connecting the collector of said output transistor to the base of said second input transistor thereby the provide positive capacitive feedback around said second transistor pair; circuit means for connecting said first and second output transistors in series across a DC potential source, said first and second output transistor being connected collector to collector through a third resistance which is in series with said first and second resistances; and means for connecting each of the wires in said higher capacitance pair to the base of a respective one of said input transistors.

Claim 13

A telephone transmission system comprising: a succession of wire sections having substantially equal shunt capacitances and at least one section having a shunt capacitance substantially larger than the other sections; a plurality of loading inductors connecting adjacent wire sections in said succession of sections; and a negative capacitance element connected to the section having the larger shunt capacitance for substantially cancelling that portion of the section'' s shunt capacitance which is in excess of the equal shunt capacitance exhibited by each of the other said sections.

Claim 14

A telephone transmission system comprising: a succession of wire sections having substantially equal shunt capacitances and at least one section having a shunt capacitance substantially larger than the other sections; a plurality of loading inductors connecting adjacent wire sections in said succession of sections; and a negative capacitance element connected to the section having the larger shunt capacitance for substantially cancelling that portion of the section'' s shunt capacitance which is in excess of the equal shunt capacitance exhibited by each of the other said sections.

Claim 15

A compensating system as set forth in claim 10 wherein said negative capacitance element includes: a first input transistor of a first conductivity type; a first output transistor of a second conductivity type which is complementary to said first type, said first input transistor and said first output transistor forming a first transistor pair; means connecting the collector of said first input transistor to the base of said first output transistor; means including a first resistance connecting the collector of said first output transistor to the emitter of said first input transistor thereby to provide negative in-phase feedback around said first transistor pair; means including a first capacitor connecting the collector of said first output transistor to the base of said first input transistor thereby to provide positive capacitive feedback around said first transistor pair; a second input transistor, said second input transistor being of said second conductivity type; a second output transistor, said second output transistor being of said first conductivity type, said second input transistor and said second output transistor forming a second transistor pair; means connecting the collector of said second input transistor to the base of said second output transistor; means including a second resistance connecting the collector of said second output transistor to the emitter of said second input transistor thereby to provide negative in-phase feedback around said second transistor pair; means including a second capacitor connecting the collector of said output transistor to the base of said second input transistor thereby to provide positive capacitive feedback around said second transistor pair; circuit means for connecting said and second output transistors in series across a DC potential source, said first and second output transistor being connected collector to collector through a third resistance which is in series with said first and second resistances; and means for connecting the base terminals of said input transistors in parallel with said larger shunt capacitance thereby to cancel the excess portion thereof.