Feedback amplifier or threshold value switch for a current feed differential stage

Abstract

A feedback amplifier which is constructed as a threshold value switch includes a current fed differential stage and additionally comprises two transistors whose emitters are each connected to one output of the differential stage with a first resistor connected between these two outputs and second and third resistors forming operating resistors connected between the supply voltage and the two transistors, each operating resistor being connected to the collector of one transistor and the base of the other transistor respectively.

What is claimed is: 
     
       1. A feedback amplifier including a current-fed differential stage having first and second outputs, said feedback amplifier additionally comprising a first transistor having an emitter connected to the first output of the differential stage; a second transistor having an emitter connected to the second output of the differential stage; a first resistor connected between both the outputs of the differential stage; a source of supply voltage; and second and third resistors comprising operating resistors connected between said supply voltage source and said two transistors, wherein said second resistor is connected to the collector of said first transistor .[.and the base of said second transistor.]., .[.and.]. said third resistor is connected to the collector of said second transistor .[.and the base of said first transistor.]. .Iadd.said feedback amplifier further including first and second feedback amplifier output means consisting of the collectors of said first and second transistors, respectively.Iaddend.. .[.2. A feedback amplifier as defined in claim 1, and comprising a fourth resistor connecting the base of said first transistor to the collector of said second transistor and a fifth resistor connecting the base of said second transistor to the collector of said 
     
     
        first transistor..]. 3. .[.A feedback amplifier as defined in claim 2, and comprising.]. .Iadd.A feedback amplifier including a current-fed differential stage having first and second outputs, said feedback amplifier additionally comprising a first transistor having an emitter connected to the first output of the differential stage; a second transistor having an emitter connected to the second output of the differential stage; a first resistor connected between both the outputs of the differential stage; a source of supply voltage; second and third resistors comprising operating resistors connected between said supply voltage source and said two transistors, wherein said second resistor is connected to the collector of said first transistor and said third resistor is connected to the collector of said second transistor; a fourth resistor connecting the base of said first transistor to the collector of said second transistor; a fifth resistor connecting the base of said second transistor to the collector of said first transistor; .Iaddend.a sixth resistor between the base and the emitter of said first transistor and a seventh resistor between the base and the emitter of said second 
     
     
        transistor. 4. A feedback amplifier as defined in claim .[.1 or.]. 3, and comprising third and fourth transistors operating as emitter followers and each having an emitter connected to a respective one of the bases of said 
     
     
        first and second transistors. 5. A feedback amplifier as defined in claim 4, and comprising connection means for connecting the collectors of said third and fourth transistors respectively to said supply voltage source, the base of said third transistor to the collector of said .[.first.]. .Iadd.second .Iaddend.transistor and the base of said fourth transistor to the collector of said .[.second.]. .Iadd.first .Iaddend.transistor. .[.6. A feedback amplifier comprising a current fed differential stage, a first transistor having an emitter connected to a first output of said differential stage, a second transistor having an emitter connected to a second output of said differential stage, a first resistor connected between both said first and second outputs of said differential stage, a third resistor forming an operating resistor connected between a supply voltage and the collector of said first transistor and the base of said second transistor and a fourth resistor forming an operating resistor connected between said supply voltage and the collector of said second transistor and the base of said first transistor..]. .Iadd.7. A feedback amplifier including a current-fed differential stage having first and second voltage inputs and first and second outputs, said feedback amplifier additionally comprising a first transistor having an emitter connected to the first output of the differential stage; a second transistor having an emitter connected to the second output of the differential stage; first and second feedback amplifier output means consisting of the collectors of said first and second transistors, respectively; a first resistor connected between both the outputs of the differential stage; a source of supply voltage; and second and third resistors comprising operating resistors connected between said supply voltage source and said two transistors, wherein said second resistor is connected to the collector of said first transistor and the base of said second transistor, said third resistor is connected to the collector of said second transistor and the base of said first transistor, and said first resistor has a resistance value that is selected based upon desired values of voltages at said first and second voltage inputs at which current from said current-fed differential stage is switched over from one of said second and third resistors to the other of such resistors. .Iaddend. .Iadd.8. A feedback amplifier as defined in claim 7, and comprising a fourth resistor connecting the base of said first transistor to the collector of said second transistor and a fifth resistor connecting the base of said second transistor to the collector of said first transistor. .Iaddend. .Iadd.9. A feedback amplifier including a current-fed differential stage having first and second outputs, said feedback amplifier additionally comprising a first transistor having an emitter connected to the first output of the differential stage; a second transistor having an emitter connected to the second output of the differential stage; a first resistor connected between both the outputs of the differential stage; a source of supply voltage; third and fourth transistors operating as emitter followers and each having an emitter connected to a respective one of the bases of said first and second transistors; and second and third resistors comprising operating resistors connected between said supply voltage source and said two transistors, wherein said second resistor is connected to the collector of said first transistor and, via said fourth transistor, to the base of said second transistor, and said third resistor is connected to the collector of said second transistor and, via said third transistor, to the base of said first transistor. .Iaddend. .Iadd.10. A feedback amplifier as defined in claim 9, and comprising connection means for connecting the collectors of said third and fourth transistors respectively to said supply voltage source, the base of said third transistor to the collector of said second transistor and the base of said fourth transistor to the collector of said first transistor. .Iaddend.