High gain differential amplifier

An amplifier comprising:

• first and second composite transistors each having an emitter coupled to a means for biasing, a base, a first collector, and a second collector;
• a third transistor having a collector coupled to another means for biasing, an emitter coupled to said base of said first transistor, and a base for receiving input signals;
• a fourth transistor having a collector coupled to said another means for biasing, an emitter coupled to said base of said second transistor, and a base for receiving second input signals;
• and
• first resistive means coupled to receive current from said second collector of said first composite transistor, and second resistive means coupled to receive current from said second collector of said second composite transistor for generating a voltage across said resistive means proportional to any difference in current through said second collectors;
• wherein said first collectors of said first and second transistors are respectively coupled to said emitters of said fourth and third transistors for positively feeding back changes in emitter current in said first and second transistors respectively to change the base-to-emitter voltages in said fourth and third transistors respectively to thereby increase the magnitude of the changes in the emitter currents in said first and second transistors respectively and amplify said difference in current through said second collectors.