Linearized amplifier core

A differential amplifier core circuit having input terminals and output terminals, comprising:

• a pair of input transistors each having a base coupled to the respective input terminal, a collector, and an emitter coupled to a common terminal through a respective resistor of a pair of first resistors;
• a pair of load circuits coupled between the collectors of the input transistors, respectively, and a power supply terminal;
• a pair of second transistors each having a base coupled to the respective collector of the input transistor, a collector coupled to the power supply terminal, and an emitter;
• a pair of third transistors each having a base coupled to the respective input terminal, a collector coupled to the respective emitter of the second transistor, and an emitter coupled to the common terminal through a respective resistor of a pair of second resistors;
• and
• a pair of output transistors each having a base coupled to the respective emitter of the second transistor, a collector coupled to the respective output terminal, and to the power supply terminal through a respective resistor of a pair of third resistors, and an emitter coupled to the common terminal through a respective resistor of a pair of fourth resistors.

A differential amplifier circuit, comprising:

• an input stage including a pair of input transistors each having a base coupled to a respective one of input terminals, a collector coupled to a power supply terminal through a respective one of load circuits and an emitter coupled to a second power supply terminal;
• an output stage including output transistors each having a base, a collector coupled to a respective one of output terminals and to the power supply terminal through a respective one of a pair of first resistors, and an emitter coupled to the second power supply terminal through a respective one of a pair of second resistors;
• and
• a buffer stage coupled between the input terminals and the collectors of the input transistors of the input stage, and the bases of the output transistors of the output stage.

A method of linearizing the input/output characteristics of a differential amplifier circuit having input transistors coupled to input terminals and output transistors coupled to output terminals, the method comprising:

• providing first and second terminals;
• providing a pair of first, second, and third transistors each having a base, a collector, and an emitter;
• for each transistor in a pair of transistors,
• coupling the base and collector of the first transistor together and to the first terminal;
• coupling the emitter of the first transistor to the respective input transistor through a respective resistor in a pair of first resistors;
• coupling the base of the second transistor to the respective input transistor;
• coupling the collector of the second transistor to the first terminal;
• coupling the emitter of the second transistor to the respective output transistor and to the collector of the third transistor;
• coupling the base of the third transistor to the respective input terminal;
• and
• coupling the emitter of the third transistor to the second terminal through a respective resistor in a pair of second resistors.