Low noise ac differential amplifier with reduced low corner frequency and current consumption

Abstract

An integrated amplifier may include a transconductance stage including a differential pair of input transistors of a first type of conductivity, respective resistive loads coupled to said input transistors, and a first bias circuit coupled to the input transistors. The first bias circuit may include a second differential pair of bias transistors having first conduction terminals coupled in common and second conduction terminals coupled to respective conduction terminals of the input transistors. The first bias circuit may also include respective second bias circuits coupled to the bias transistors to enable the input transistors in a conduction state with the input transistors being biased by a same respective bias current that flows through the respective input transistors. The first bias circuit may also include a capacitive network coupled to the bias transistors to define with the input transistors a feedback loop.