US3758791A — Current switch circuit

Claim 1

Independent Claim 226 words

A current switch circuit comprising: at least one input transistor to whose base an input signal is applied; a reference transistor to whose base a reference voltage is applied and whose emitter is connected with the emitter of said input transistor; load resistors connected respectively with the colleCtors of said input and reference transistors; emitter followers connected respectively with the collectors of said input and reference transistors; two diode circuits connected in parallel between the collectors of said input and reference transistors, each of said diode circuits comprising a diode and a resistor connected in series with said diode for controlling current flowing through said diode, and wherein said diodes disposed in said two diode circuits are oriented in mutually opposite directions with respect to each other; emitter current regulating means connected in common with the emitters of said input and reference transistors for regulating the emitter current flowing through the commonly connected emitters, so that said emitter current has a certain temperature coefficient; and a power supply source having a first power terminal connected with said load resistors respectively and a second power terminal connected with said emitter current regulating means for providing a power potential between said first and second power terminals, whereby the D.C. voltage levels of the output signals derived out from said emitter followers changeable due to temperature change are stabilized.

Claim 2

Dependent Claim 226 words

A current switch circuit comprising: at least one input transistor to whose base an input signal is applied; a reference transistor to whose base a reference voltage is applied and whose emitter is connected with the emitter of said input transistor; load resistors connected respectively with the colleCtors of said input and reference transistors; emitter followers connected respectively with the collectors of said input and reference transistors; two diode circuits connected in parallel between the collectors of said input and reference transistors, each of said diode circuits comprising a diode and a resistor connected in series with said diode for controlling current flowing through said diode, and wherein said diodes disposed in said two diode circuits are oriented in mutually opposite directions with respect to each other; emitter current regulating means connected in common with the emitters of said input and reference transistors for regulating the emitter current flowing through the commonly connected emitters, so that said emitter current has a certain temperature coefficient; and a power supply source having a first power terminal connected with said load resistors respectively and a second power terminal connected with said emitter current regulating means for providing a power potential between said first and second power terminals, whereby the D.C. voltage levels of the output signals derived out from said emitter followers changeable due to temperature change are stabilized.

Claim 3

Dependent Claim 62 words

A current switch circuit as defined in claim 1, wherein said diodes in said diode circuits respectively provide a forward voltage drop whose temperature coefficient is substantially the same as that of the base-emitter forward voltage drop in said input and the reference transistors, and said resistors in said diode circuits respectively have the same resistance as that of said load resistors.

Claim 4

Dependent Claim 35 words

A current switch circuit as defined in claim 2, which further comprises a temperature-compensated biasing circuit which produces a reference voltage having a substantially zero temperature coefficient coupled to the base of said reference transistor.

Claim 5

Dependent Claim 58 words

A current switch circuit as defined in claim 1, wherein said emitter current regulating means comprises a first transistor whose collector is connected in common with the emitters of said input and reference transistors and to whose base a regulation voltage is applied, and means for connecting the emitter of said first transistor with said second power terminal.

Claim 6

Dependent Claim 128 words

A current switch circuit as defined in claim 4, which further comprises a temperature-compensated biasing circuit including: a second transistor having its emitter-collector circuit coupled between said first power supply terminal and the base of said reference transistor; a first biasing resistor coupled between the base of said second transistor and said first power supply terminal; at least one diode and a second biasing resistor connected in series between said second power supply terminal and the base of said second transistor; and a voltage dividing circuit which comprises first and second impedance means connected in series between the emitter of said second transistor and the second power supply terminal, the common connection of said first and second impedance means being connected with the base of said first transistor.

Claim 7

Dependent Claim 61 words

A current switch circuit as defined in claim 5, wherein said first and second impedance means are composed of third and fourth biasing resistors respectively, and said means for connecting the emitter of said first transistor with said second power supply terminal is composed of a feedback resistor whose resistance value is equal to one-half of that of said load resistors.

Claim 8

Dependent Claim 63 words

A current switch circuit as defined in claim 5, wherein said first impedance means is composed of a diode, said second impedance element is composed of a biasing resistor, and said means for connecting the emitter of said first transistor with said second power supply terminal is composed of a feedback resistor whose resistance value is equal to that of said load resistors.

Claim 9

Dependent Claim 114 words

A current switch circuit as defined in claim 5, wherein said first and second impedance means are composed of a biasing resistor and a diode respecTively, and said means for connecting the emitter of said first transistor with said first power supply terminal is composed of a conductor for directly connecting therebetween, the resistance value RD of said first impedance means being so selected as to satisfy the equation 1/2 RCN RD/ gamma , wherein RCN is the resistance value of said load resistors and gamma is the ratio of the area of the emitter junction in the first transistor to that of the junction in said diode which comprises said second impedance means.

Claim 10

Dependent Claim 173 words

A current switch comprising: at least one input transistor having an emitter, a base and a collector; means for connecting a biasing power supply across the collector and emitter of said input transistor; first and second output circuits, each of which is connected to receive a signal from the collector of said at least one input transistor and to provide output signals therefrom, the output of one of said output circuits being at a first level while the output of the other of said output circuits is at a level, different from said first output level; and means, coupled between said pair of output circuits for maintaining the two different output levels from each of said first and second output circuits substantially constant over a prescribed temperature range, including a pair of pn junction-resistor circuits, each of which comprises a pn junction and a resistor connected in series, said pn junction-resistor circuits being connected in parallel, and wherein the pn junctions are oppositely poled with respect to each other within said parallel-connected circuits.

Claim 11

Dependent Claim 173 words

A current switch comprising: at least one input transistor having an emitter, a base and a collector; means for connecting a biasing power supply across the collector and emitter of said input transistor; first and second output circuits, each of which is connected to receive a signal from the collector of said at least one input transistor and to provide output signals therefrom, the output of one of said output circuits being at a first level while the output of the other of said output circuits is at a level, different from said first output level; and means, coupled between said pair of output circuits for maintaining the two different output levels from each of said first and second output circuits substantially constant over a prescribed temperature range, including a pair of pn junction-resistor circuits, each of which comprises a pn junction and a resistor connected in series, said pn junction-resistor circuits being connected in parallel, and wherein the pn junctions are oppositely poled with respect to each other within said parallel-connected circuits.

Claim 12

Dependent Claim 71 words

A current-switch according to claim 9, further including a reference transistor having an emitter, a base, and a collector, the emitter of said reference transistor coupled to the emitter of said at least one input transistor, and the collector of said reference transistor being connected to one end of said pn junction-resistor circuit, the other end of said pn junction -resistor circuit being connected to the collector of said input transistor.

Claim 13

Dependent Claim 31 words

A current switch according to claim 10, further including an emitter current regulating means coupled in series between the emitters of said input and reference transistor and a power supply terminal.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1976-09-10	1977-03-12	1977-09-11	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1980-09-10	1981-03-12	1981-09-11	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1984-09-10	1985-03-12	1985-09-11	$7700.00	Window Closed / Lapsed

Current switch circuit

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