Operational amplifier with elimination of offset voltage

摘要

An operational amplifier may include a differential stage comprising two transistors whose gates are respectively linked to the two inputs of the operational amplifier. The sources of the two transistors may be linked to a first current source whose delivered current depends negatively on temperature variations and to a second current source whose delivered current is proportional to absolute temperature. The sum of these two currents may be less dependent on temperature, in that this link of the sources of the two transistors with the two current sources is effected respectively by way of two resistors, and in that the current which passes through the two transistors is imposed of proportional with temperature type, so as to allow substantially temperature-independent elimination of the offset voltage of the operational amplifier while obtaining a temperature-independent constant gain-bandwidth product.

主权项

1. An amplifier comprising:
first and second inputs; first and second current sources; and a differential stage comprising first and second transistors having gate terminals respectively coupled to said first and second inputs, and source terminals respectively coupled to said first and second current sources; said first current source configured to generate a first current negatively dependent on temperature; said second current source configured to generate a second current being proportional to the temperature, thereby obtaining a temperature-independent constant gain-bandwidth product.