Differential input stage with wide input signal range and stable transconductance

A system, comprising:

• a differential input transistor pair (DITP) comprising first and second transistors;
• a first feedback loop comprising a first resistor and third, fourth, and fifth transistors, the third transistor coupled to the first transistor;
• a second feedback loop comprising a second resistor, sixth and seventh transistors, and the fifth transistor, the sixth transistor coupled to the second transistor;
• and
• a tail current transistor coupled to the first and second transistors, the tail current transistor configured to mirror a current flowing through the fifth transistor.

A method, comprising:

• receiving a differential input voltage at a differential input transistor pair (DITP) of an analog integrated circuit (IC), a tail current transistor supplying a tail current to the DITP;
• in response to the differential input voltage being in a first range, controlling a first minimum current in a first feedback loop based on a first sizing ratio of multiple transistors in the first feedback loop and controlling a second minimum current in a second feedback loop based on a second sizing ratio of additional transistors in the second feedback loop, the first and second minimum currents together compose the tail current, the tail current determines a transconductance of the DITP;
• and
• in response to the differential input voltage being in a second range, providing an output current from the DITP based on a resistor having a resistance determined based on the transconductance of the DITP when the differential input voltage is in the first range.