Output circuit for comparators

Claim 2

An output circuit for providing the saturation of an output transistor with a current whose magnitude is independent of a supply voltage comprising: means coupled to said supply voltage for generating a current, said means including a second transistor; a multiple-collector transistor, with the emitter of said multiple-collector transistor coupled to said supply voltage; means coupled from one of said collectors to the other of said collectors for drawing a current from the other of said collectors, said current having a magnitude independent of said supply voltage, the current in the other of said collectors causing the current in said one collector to be independent of said supply voltage such that the current through said multiple-collector transistor is independent of said supply voltage, whereby the voltage at the base of said multiplecollector transistor tracks variations in said supply voltage at a fixed voltage therebeneath, the base of said multiplecollector transistor being coupled to the base of said second transistor such that the transistor in said current generating means generates a constant current; and means for connecting said generating means to the base of said saturable output transistor for providing current to said base of said saturable output transistor.

Claim 3

The circuit as recited in claim 1 and further including: means for selectively shunting said current away from the base of said saturable output transistor whenever desired, whereby said saturable output transistor performs a switching function which is independent of supply voltage variations.

Claim 4

The circuit as recited in claim 1 and including a further output transistor wherein: said saturable output transistor is used to drive said further output transistor into saturation, said circuit further including current limiting means, operating independently of variations in said supply voltage, said current limiting means including a current source havIng a third transistor and a resistor connected in series therewith between said supply voltage and one of the main electrodes of said saturable output transistor, with the other of the main electrodes of said saturable output transistor coupled to the base of said further output transistor; and means for providing a voltage independent of said supply voltage to the base of said third transistor whereby said current limiting means functions independently of said supply voltage such that the total amount of current that said output circuit can sink is independent of said supply voltage.

Claim 5

The circuit as recited in claim 3 wherein said means for providing a voltage independent of said supply voltage to the base of the transistor in said transistor current source includes: a multiple-collector transistor, with the emitter of said multiple-collector transistor coupled to said supply voltage; means coupled from one of said collectors to the other of said collectors for drawing a current in the other of said collectors having a magnitude independent of said supply voltage, the current in the other of said collectors causing the current in said one collector to be independent of said supply voltage; and resistive means interposed between said one collector and ground, the current through said resistive means being independent of said supply voltage whereby the voltage at the ungrounded end of said resistive means is independent of supply voltage because of the constant current therethrough, said ungrounded end being coupled to the base of the transistor in said transistor current source.

Claim 6

The circuit as recited in claim 3 further including: a power transistor, said further output transistor being used to drive said power output transistor with one main electrode of said further output transistor coupled to the base of said power output transistor, whereby said power transistor carries the majority of any load current whenever a load is connected in series therewith between said supply voltage and ground.

Claim 7

The circuit as recited in claim 5 wherein said further output transistor and said power transistor are coupled in a Darlington configuration.

Claim 8

A switching circuit having a switching function independent of a supply voltage comprising in combination: a comparator circuit for comparing an input signal with a reference voltage and for rendering conductive a first transistor whenever said input signal has a first predetermined relationship with said reference voltage; and an output circuit comprising: means coupled to said supply voltage for generating a current, said means including a second transistor; means for supplying the base of said second transistor with a voltage that is a fixed voltage below said supply voltage, the current generated by said current generating means being constant both with respect to AC signals and with respect to variations in said supply voltage; a saturable output transistor; means for connecting said generating means to the base of said saturable output transistor for providing current to said base of said saturable output transistor, and for connecting one of the main terminals of said first transistor to the base of said saturable output transistor and the other of the main terminals of said first transistor to ground, such that said first transistor shunts the current coupled to said saturable output transistor away from said saturable output transistor to ground whenever said first transistor is rendered conductive, whereby said saturable output transistor is saturated whenever said input signal is in a second predetermined relationship with respect to said reference voltage.

Claim 9

A switching circuit having a switching function independent of a supply voltage comprising in combination: a comparator circuit for comparing an input signal with a reference voltage and for rendering conductive a first transistor whenever said input signal has a first predetermined relationship with said reference voltage; and an output circuit comprising: means coupled to said supply voltage for generating a current, said means including a second transistor; means for supplying the base of said second transistor with a voltage that is a fixed voltage below said supply voltage, the current generated by said current generating means being constant both with respect to AC signals and with respect to variations in said supply voltage; a saturable output transistor; means for connecting said generating means to the base of said saturable output transistor for providing current to said base of said saturable output transistor, and for connecting one of the main terminals of said first transistor to the base of said saturable output transistor and the other of the main terminals of said first transistor to ground, such that said first transistor shunts the current coupled to said saturable output transistor away from said saturable output transistor to ground whenever said first transistor is rendered conductive, whereby said saturable output transistor is saturated whenever said input signal is in a second predetermined relationship with respect to said reference voltage.

Claim 10

A bias supply circuit for providing voltages which are at a fixed potential below said supply voltage comprising: a multiple-collector transistor, with the emitter of said multiple-collector transistor coupled to said supply voltage; and means coupled from one of the collectors of saiD transistor to the other of its collectors for drawing a current in the other of said collectors such that the magnitude of the current drawn is independent of said supply voltage, the current in the other of said collectors causing a carrier emission in said transistor such that current in said one of said collectors is independent of said supply voltage and such that the current through said multiple-collector transistor is constant with respect to variations in said supply voltage whereby the voltage at the base of said multiple-collector transistor tracks variations in said supply voltage at a fixed voltage therebeneath due to the constant current through said multiple-collector transistor, said base forming an output terminal for said bias supply having a voltage thereat at a fixed voltage below said supply voltage.

Claim 11

A bias supply circuit for providing voltages which are at a fixed potential below said supply voltage comprising: a multiple-collector transistor, with the emitter of said multiple-collector transistor coupled to said supply voltage; and means coupled from one of the collectors of saiD transistor to the other of its collectors for drawing a current in the other of said collectors such that the magnitude of the current drawn is independent of said supply voltage, the current in the other of said collectors causing a carrier emission in said transistor such that current in said one of said collectors is independent of said supply voltage and such that the current through said multiple-collector transistor is constant with respect to variations in said supply voltage whereby the voltage at the base of said multiple-collector transistor tracks variations in said supply voltage at a fixed voltage therebeneath due to the constant current through said multiple-collector transistor, said base forming an output terminal for said bias supply having a voltage thereat at a fixed voltage below said supply voltage.

Claim 12

A bias supply for providing voltages which are independent of supply voltage changes comprising: a multiple-collector transistor, with the emitter thereof coupled to said supply voltage; means coupled from one of said collectors to the other of said collectors for drawing a current in the other of said collectors such that the magnitude of said current is independent of said supply voltage, the current in the other of said collectors causing the current in said one collector to be constant and independent of said supply voltage; and first resistance means coupled between said one collector and ground, the ungrounded side of said resistance means providing a voltage independent of variations in said supply voltage due to the constant current through said first resistance means.

Claim 13

A bias supply for providing voltages which are independent of supply voltage changes comprising: a multiple-collector transistor, with the emitter thereof coupled to said supply voltage; means coupled from one of said collectors to the other of said collectors for drawing a current in the other of said collectors such that the magnitude of said current is independent of said supply voltage, the current in the other of said collectors causing the current in said one collector to be constant and independent of said supply voltage; and first resistance means coupled between said one collector and ground, the ungrounded side of said resistance means providing a voltage independent of variations in said supply voltage due to the constant current through said first resistance means.

Claim 14

The bias supply as recited in claim 9 wherein the voltage at the base of said multiple-collector transistor is a fixed amount below said supply voltage due to a constant current being drawn therethrough.

Claim 15

The bias supply as recited in claim 9 wherein said means for drawing a current includes: a second transistor with its base coupled to the ungrounded end of said resistance means; a second resistance means coupled between ground and one terminal of said second transistor, the other main terminal of said second transistor being coupled to the other of the collectors of said multiple-collector transistor; and a third transistor having its emitter coupled to the base of said multiple-collector transistor, its collector grounded and its base coupled to the other of the collectors of said multiple-collector transistor.

Claim 16

The bias supply as recited in claim 11 and further including a starter circuit comprising: a third and fourth resistance means coupled in series between said supply voltage and ground; and a fourth transistor having its main electrodes coupled to corresponding main electrodes of said second transistor, and having its base coupled to the junction between said third and fourth resistance means, said second and fourth transistors functioning as a differential amplifier, said fourth resistance means having a value less than that of said first resistance means whereby said fourth transistor draws current until said second transistor is biased into conduction at which point said fourth transistor turns OFF due to differential transistor action.