Balanced double-to-single-ended converter stage for use with a differential amplifier

Claim 2

In a circuit having a balanced signal source providing a balanced signal between first and second electrodes thereof, a balanced-to-unbalanced converter suitable for transforming the balanced signal into an unbalanced signal at an output terminal thereof and for applying substantially the same active loads to the first and secoNd electrodes of the balanced signal source, the balanced-to-unbalanced converter including in combination: power supply connecting means for providing voltage potentials, said power supply connecting means having an output terminal and a reference terminal; first active load means for providing an active load to the first electrode of the balanced signal source, said first active load means having a first terminal coupled to the first electrode of the balanced signal source, a second terminal coupled to said output terminal of said power supply connecting means, a third terminal coupled to said reference terminal of said power supply connecting means, and an output terminal, said first active load means being responsive to said voltage potentials to provide an active impedance having first predetermined electrical characteristics to the first electrode of the balanced signal source; and second active load means for providing an active load to the second electrode of the balanced signal source, said second active load means having a first terminal coupled to the second electrode of the balanced signal source, a second terminal coupled to said output terminal of said power supply connecting means, a third terminal coupled to said reference terminal of said power supply connecting means, a fourth terminal coupled to said output terminal of said first active load means, and a fifth terminal providing the output terminal of the balancedto-unbalanced converter, said second active load means being responsive to said voltage potentials to provide an active impedance having second predetermined electrical characteristics to the second electrode of the balanced signal source, said second predetermined electrical characteristics being substantially the same as said first predetermined electrical characteristics of said first active load means to cause substantially equal active impedances to be applied to the first and second electrodes of the balanced signal source.

Claim 3

The combination of claim 1 wherein: said first active load means is responsive to an increase in signal amplitude at the first electrode of the balanced signal source to cause the output signal amplitude to change in a first direction; and said second active load means is responsive to a decrease in the signal amplitude at the second electrode of the balanced signal source to cause the output signal amplitude to also change in the first direction.

Claim 4

The combination of claim 1 wherein said first active load means includes: current supply means for providing a constant current, said current supply means having first and second terminals, said first terminal being connected to said output terminal of said power supply connecting means; and first electron control means having a first electrode connected to said reference terminal of said power supply connecting means, a control electrode connected to the first electrode of the balanced signal source, and a second electrode connected to said second terminal of said current supply means, said first electron control means clamping the first electrode of the balanced signal source to a predetermined voltage having a fixed relationship with respect to the potential at said reference terminal of said power supply connecting means.

Claim 5

The combination of claim 3 wherein: said first electron control means is a bipolar transistor of a first conductivity type having emitter, base, and collector electrodes corresponding respectively to said first, control and second electrodes; and said bipolar transistor having a base-to-emitter junction for clamping the first electrode of the balanced signal source to said predetermined voltage which is a substantially fixed amount greater than said potential at said reference terminal of said power supply connecting means.

Claim 6

The combination of claim 3 wherein said first active load means further includes: second electron control means having a first electrode connected tO said output terminal of said first active load means, a second electrode connected to said output terminal of said power supply connecting means and a control electrode connected to said second terminal of said current supply means and to said second electrode of said first electron control means; and third electron control means having a first electrode connected to said first electrode of said second electron control means, and a second electrode connected to the first electrode of the balanced signal source.

Claim 7

The combination of claim 1 wherein said second active load means includes: current supply means for supplying a constant current, said current supply means having first and second terminals, said first terminal being connected to said output terminal of said power supply connecting means; and electron control means having a first electrode connected to said reference terminal of said power supply connecting means, a control electrode connected to the second electrode of the balanced signal source and a second electrode connected to said second terminal of said current supply means, said electron control means clamping the second electrode of the balanced signal source to a predetermined voltage having a fixed relationship with respect to said potential at said reference terminal of said power supply connecting means.

Claim 8

The combination of claim 6 wherein: said electron control means is a bipolar transistor of a first conductivity type having emitter, base and collector electrodes corresponding respectively to said first, control and second electrodes of said electron control means; and said bipolar transistor having a base-to-emitter junction for clamping the second electrode of the balanced signal source to said predetermined voltage which is a substantially fixed amount greater than said potential at said reference terminal of said power supply connecting means.

Claim 9

A double-to-single ended converter circuit suitable for being connected to first and second output terminals of a differential amplifier, the converter transforming the balanced signal occurring at the output terminals of the differential amplifier into an unbalanced signal at an output terminal thereof and including in combination: first power supply connecting means for supplying a voltage of a first magnitude between an output terminal and a reference terminal thereof; second power supply connecting means for supplying a bias voltage between an output terminal and said reference terminal, first current supply means having a power terminal connected to said output terminal of said first power supply connecting means and having an output terminal; second current supply means having a power terminal connected to said output terminal of said first power supply connecting means and having an output terminal; first electron control means having a first electrode, a second electrode connected to said output terminal of said first power supply connecting means and a control electrode connected to said output terminal of said first current supply means; second electron control means having a first electrode connected to said first electrode of said first electron control means, a second electrode, and a control electrode connected to said output terminal of said second power supply connecting means; third electron control means having a first electrode connected to said first electrode of said first electron control means and to said first electrode of said second electron control means, a second electrode, and a control electrode connected to said control electrode of said second electron control means and to said output terminal of said second power supply connecting means; fourth electron control means having a first electrode coupled to said reference terminal of said first power supply connecting means, a second electrode connected to said output terminal of said first current supply means and to said control electrode of said first electron control means, and a control electrode connected to the first output terminal of the differential amplifier and coupled to said second electrode of said second electron control means; and fifth electron control means having a first electrode coupled to said reference terminal of said first power supply connecting means, a second electrode connected to said output terminal of said second current supply means, said second electrode of said fifth electron control means providing an output terminal for the converter, and a control electrode connected to the second output terminal of the differential amplifier and coupled to said second electrode of said third electron control means.

Claim 10

A double-to-single ended converter circuit suitable for being connected to first and second output terminals of a differential amplifier, the converter transforming the balanced signal occurring at the output terminals of the differential amplifier into an unbalanced signal at an output terminal thereof and including in combination: first power supply connecting means for supplying a voltage of a first magnitude between an output terminal and a reference terminal thereof; second power supply connecting means for supplying a bias voltage between an output terminal and said reference terminal, first current supply means having a power terminal connected to said output terminal of said first power supply connecting means and having an output terminal; second current supply means having a power terminal connected to said output terminal of said first power supply connecting means and having an output terminal; first electron control means having a first electrode, a second electrode connected to said output terminal of said first power supply connecting means and a control electrode connected to said output terminal of said first current supply means; second electron control means having a first electrode connected to said first electrode of said first electron control means, a second electrode, and a control electrode connected to said output terminal of said second power supply connecting means; third electron control means having a first electrode connected to said first electrode of said first electron control means and to said first electrode of said second electron control means, a second electrode, and a control electrode connected to said control electrode of said second electron control means and to said output terminal of said second power supply connecting means; fourth electron control means having a first electrode coupled to said reference terminal of said first power supply connecting means, a second electrode connected to said output terminal of said first current supply means and to said control electrode of said first electron control means, and a control electrode connected to the first output terminal of the differential amplifier and coupled to said second electrode of said second electron control means; and fifth electron control means having a first electrode coupled to said reference terminal of said first power supply connecting means, a second electrode connected to said output terminal of said second current supply means, said second electrode of said fifth electron control means providing an output terminal for the converter, and a control electrode connected to the second output terminal of the differential amplifier and coupled to said second electrode of said third electron control means.

Claim 11

The converter circuit of claim 8 further including: sixth electron control means having a first electrode, a second electrode connected to said output terminal of said first power supply connecting means and a control electrode connected to said output terminal of said second current supply means and to said second electrode of said fifth electron control means; and third current supply means having a terminal connected to said reference terminal of said first power supply connecting means and a second terminal connected to said first electrode of said sixth electron control means.

Claim 12

The converter circuit of claim 8 further including: another electron control means having a first electrode connected to said control electrode of said fourth electron control means, a control electrode connected to said second electrode of said second electron control means, and a second electrode connected to said output terminal of said first power supply connecting means.

Claim 13

The converter circuit of claim 8 further including: further electron control means having a first electrode connected to said control electrode of said fifth electron control means, a second electrode connected to said output terminal of said first power supply connecting means, and a control electrode connected to said second electrode of said third electron control means.

Claim 14

The converter circuit of claim 8 wherein said first, fourth and fifth electron control means are transistors of a first conductivity type, and said second and third electron control means are transistors of a second conductivity type.

Claim 15

The converter circuit of claim 8 wherein at least one of said current supply means includes: a bipolar transistor having an emitter electrode connected to one of said terminals of said first power supply connecting means, a collector electrode connected to said output terminal of said at least one of said current supply means, and a base electrode; and a diode connected between said base and emitter electrodes of said bipolar transistor to control the base-to-emitter voltage thereof to thereby control the collector current of said bipolar transistor which is provided at said output terminal of said at least one of said current supply means.

Claim 16

The converter circuit of claim 9 wherein said sixth electron control means is a transistor of the first conductivity type.

Claim 17

The converter circuit of claim 12 wherein said transistors of said first conductivity type are NPN bipolar transistors and said transistors of said second conductivity type are PNP bipolar transistors.

Claim 18

The converter circuit of claim 15 wherein said first, second and control electrodes of said electron control means respectively correspond to emitter, collector and base electrodes of said bipolar transistors.

Claim 19

The converter circuit of claim 10 further including capacitive means coupling said control electrode of said another electron control means to said second electrode of said fourth electron control means.

Claim 20

The converter circuit of claim 11 further including capacitive means coupling said control electrode of said further electron control means to said second electrode of said fifth electron control means.

Claim 21

In a circuit having a balaNced signal source providing a balanced signal between first and second output terminals thereof, a balanced-to-unbalanced converter suitable for transforming the balanced signal into an unbalanced signal at an output terminal thereof and for applying substantially equal quiescent voltages and currents to the first and second output terminals of the balanced signal source, the balanced-to-unbalanced converter including in combination: differential amplifier means for amplifying said balanced signal, said differential amplifier means having first and second output terminals, a first input terminal coupled to the first output terminal of the balanced signal source and a second input terminal coupled to the second output terminal of the balanced signal source; power supply connecting means for providing voltages, said power supply connecting means having an output terminal, a bias terminal, and a reference terminal; first active load means for said first output terminal of said differential amplifier means, said first active load means having a first terminal coupled to said first output terminal of said differential amplifier means, a second terminal coupled to said output terminal of said power supply connecting means, a third terminal connected to said reference terminal of said power supply connecting means, a bias electrode connected to said bias terminal of said power supply connecting means, and an output terminal, said first active load means applying a predetermined voltage and current to said first output terminal of said differential amplifier means during quiescent operation; and second active load means for said second output terminal of said differential amplifier means, said second active load means having a first terminal coupled to said second output terminal of said differential amplifier means, a second terminal coupled to said output terminal of said power supply connecting means, a third terminal coupled to said reference terminal of said power supply connecting means, a fourth terminal coupled to said output terminal of said first active load means, a bias electrode connected to said bias terminal of said power supply connecting means and a fifth terminal connected to the output terminal of the balanced-to-unbalanced converter, said second active load means applying a voltage and current which are substantially equal to said predetermined voltage and current to said second output terminal of said differential amplifier means during quiescent operation.

Claim 22

In a circuit having a balaNced signal source providing a balanced signal between first and second output terminals thereof, a balanced-to-unbalanced converter suitable for transforming the balanced signal into an unbalanced signal at an output terminal thereof and for applying substantially equal quiescent voltages and currents to the first and second output terminals of the balanced signal source, the balanced-to-unbalanced converter including in combination: differential amplifier means for amplifying said balanced signal, said differential amplifier means having first and second output terminals, a first input terminal coupled to the first output terminal of the balanced signal source and a second input terminal coupled to the second output terminal of the balanced signal source; power supply connecting means for providing voltages, said power supply connecting means having an output terminal, a bias terminal, and a reference terminal; first active load means for said first output terminal of said differential amplifier means, said first active load means having a first terminal coupled to said first output terminal of said differential amplifier means, a second terminal coupled to said output terminal of said power supply connecting means, a third terminal connected to said reference terminal of said power supply connecting means, a bias electrode connected to said bias terminal of said power supply connecting means, and an output terminal, said first active load means applying a predetermined voltage and current to said first output terminal of said differential amplifier means during quiescent operation; and second active load means for said second output terminal of said differential amplifier means, said second active load means having a first terminal coupled to said second output terminal of said differential amplifier means, a second terminal coupled to said output terminal of said power supply connecting means, a third terminal coupled to said reference terminal of said power supply connecting means, a fourth terminal coupled to said output terminal of said first active load means, a bias electrode connected to said bias terminal of said power supply connecting means and a fifth terminal connected to the output terminal of the balanced-to-unbalanced converter, said second active load means applying a voltage and current which are substantially equal to said predetermined voltage and current to said second output terminal of said differential amplifier means during quiescent operation.