Current scaling apparatus
First Claim
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1. A current scaling apparatus comprising, in combination:
- first and second and third and fourth transistors, each having base and emitter electrodes and a base-emitter junction therebetween and having a collector electrode, said first and said second transistors being of the same conductivity type as each other and having interconnected emitter electrodes, said third and said fourth transistors being of the same conductivity type as each other and having interconnected emitter electrodes;
means operating said third and said fourth transistors with different densities of current flow through their respective base-emitter junctions for defining a difference between their respective base potentials;
means for scaling up the difference between the base potentials of said third and said fourth transistors by a fixed ratio; and
means applying the scaled up difference potential between the base electrodes of said first and said second transistors for determining the ratio between their respective collector currents.
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Abstract
The difference between the base potentials of a pair of transistors, which are interconnected at their emitter electrodes and operated with different densities of current flow through their base-emitter junctions, is scaled up by a fixed ratio and applied between the base electrodes of another pair of transistors with interconnected emitter electrodes to cause their collector currents to flow in a desired ratio.
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Citations
27 Claims
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1. A current scaling apparatus comprising, in combination:
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first and second and third and fourth transistors, each having base and emitter electrodes and a base-emitter junction therebetween and having a collector electrode, said first and said second transistors being of the same conductivity type as each other and having interconnected emitter electrodes, said third and said fourth transistors being of the same conductivity type as each other and having interconnected emitter electrodes; means operating said third and said fourth transistors with different densities of current flow through their respective base-emitter junctions for defining a difference between their respective base potentials; means for scaling up the difference between the base potentials of said third and said fourth transistors by a fixed ratio; and means applying the scaled up difference potential between the base electrodes of said first and said second transistors for determining the ratio between their respective collector currents. - View Dependent Claims (2)
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3. A current scaling apparatus for responding to an input current to supply an output current proportional to its said input current, said current scaling apparatus comprising:
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first and second and third and fourth junction transistors, all made of the same basic semiconductive material and operated at substantially the same absolute temperature T, each having base and emitter electrodes with a base-emitter junction therebetween and each having a collector electrode, said first and said second transistors being of the same conductivity type as each other and said third and said fourth transistors being of the same conductivity type as each other; an input terminal for receiving said input current, galvanically coupled to the collector electrode of said first transistor; an output terminal for delivering said output current to which the collector electrode of said second transistor is galvanically coupled; a common terminal for return of said input and output currents, to which the emitter electrodes of said first and said second transistors are directly connected without substantial intervening impedance; means applying direct-coupled degenerative collector-to-base to said first transistor for regulating its base potential to condition it to accept as collector current essentially the entire input current as received at said input terminal and galvanically coupled to its collector electrode; a potential divider having an input port connected between the base electrodes of said first and said second transistors and having an output port connected between the base electrodes of said third and said fourth transistors; first direct current conductive means, linking said common terminal and a first circuit node, to which node the emitter electrodes of said third and said fourth transistors are directly connected without substantial intervening impedance; differential combining means for differentially combining the collector currents of said third and said fourth transistors to develop an error signal when the potential between the base electrodes of said thid and said fourth transistors departs from a predetermined value; and means responsive to said error signal for applying a current proportional to said error signal, applied at the base electrode of said second transistor in a sense to degenerate said error signal. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. Apparatus comprising:
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first and second transistors of the same conductivity type, each having base and emitter electrodes with a base-emitter junction therebetween, having a collector electrode, and being operated at substantially the same temperature T; means for applying a current to the interconnection of the emitter electrodes of said first and said second transistors which is of a polarity tending to forward bias their respective base-emitter junctions and thus cause respective collector current flows through their respective collector electrodes; means for differentially combining in predetermined proportion the collector currents of said first and said second transistors to obtain an error signal; a number, at least one, of further semiconductor junctions operated at substantially the temperature T; a plurality of resistive means with resistances in fixed proportion to each other connected in series connection with said number of further semiconductor junctions; means for applying a current proportional to said error signal to said series connection in a sense to forward bias each of said number of further semiconductor junctions, thereby to develop an output potential across said series connection characteristic of a multiple of the offset potential across a semiconductor junction operated at higher current density than each said further semiconductor junction; and means applying a portion of said output potential, as appears across one of said resistive means, between the base electrodes of said first and said second transistors in a sense for completing a degenerative feedback loop for regulating this potential to a predictable value. - View Dependent Claims (21, 22, 23)
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24. Apparatus comprising:
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a first terminal connected to a point of reference potential, a second terminal, and a third terminal; first and second transistors of the same conductivity type, each having base and emitter electrodes with a base-emitter junction therebetween, having a collector electrode, and being operated at substantially the same temperature T; means for applying a current to the interconnection of the emitter electrodes of said first and said second transistors which is of a polarity tending to forward bias their respective base-emitter junctions and thus cause respective collector current flows through their respective collector electrodes; means for differentially combining in predetermined proportion the collector currents of said first and said second transistors to obtain an error signal; a number, at least one, of further semiconductor junctions operated at substantially the temperature T arranged in a current path between said first and said second terminals with no substantial intervening impedance; an input current source connected between said first and said second terminals for applying an input current of a polarity to forward bias each said further semiconductor junction connected therein, responsive to which an offset potential appears between said first and said second terminals; resistance means connected between said second terminal and said third terminal; means for applying a current proportional to said error signal to said series connection, responsive to which a potential appears between said second and said third terminals; means applying the potential appearing across a portion of said resistance means between the base electrodes of said first and second transistors, thereby completing a degenerative feedback loop for regulating this potential to a predictable value; and means connected between said first and said third terminals for utilizing the potential appearing therebetween. - View Dependent Claims (25, 26, 27)
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Specification