SIGNAL AMPLIFIER AND BALANCED INPUT/OUTPUT DIFFERENTIAL AMPLIFIER

摘要

The invention provides a balanced input/output amplifier having a low common mode gain and high input impedance. The balanced input/output amplifier uses the noninverting inputs of two pairs of differential inputs as balanced inputs to achieve a high input impedance, and uses the in-phase components of the differential input to control input common mode so as to prevent the saturation of the input circuit. When the input common mode potential changes and the potentials of the two noninverting inputs of the differential inputs connecting a positive input and a negative input exceed the potential of the inverting input of the differential inputs, the potential at the input common mode control output rises until the potential difference disappears. When the potentials of the two noninverting inputs of the differential inputs fall below the potential of the corresponding inverting inputs of the differential inputs, the potential of an input common mode control output (11) falls until the potential difference disappears so that the differential input may not be saturated.