Linear differential amplifier with high input impedance

A differential amplifier with an amplifier circuit comprising two differential pairs,

• wherein a first differential pair is connected in series to a second differential pair,
• wherein the second differential pair is connected at control terminals in a crosswise manner at least indirectly to a differential output signal of the first differential pair,
• wherein the first differential pair and the second differential pair form a first differential current path and a second differential current path,
• wherein a first emulation device is connected in parallel to the first current path, and that a second emulation device is connected in parallel to the second current path,
• wherein the first differential pair comprises a first transistor and a second transistor,
• wherein the second differential pair comprises a third transistor and a fourth transistor,
• wherein the first emulation device comprises a fifth transistor and a seventh transistor,
• wherein the second emulation device comprises a sixth transistor and an eighth transistor,
• wherein first terminals of the first transistor and of the second transistor are each connected to an output,
• wherein a second terminal of the first transistor is connected to a first terminal of the third transistor, and a second terminal of the second transistor is connected to a first terminal of the fourth transistor,
• wherein a second terminal of the third transistor is connected via a first resistor and a current source to earth, and a second terminal of the fourth transistor is connected via a second resistor and the current source to earth,
• wherein third terminals of the first transistor and the second transistor are each connected to an input, and
• wherein the second terminal of the first transistor is connected to a third terminal of the fourth transistor, and the second terminal of the second transistor is connected to a third terminal of the third transistor.