Method of limiting the noise bandwidth of a bandgap voltage generator and relative bandgap voltage generator

摘要

A method of limiting the noise bandwidth of a closed loop bandgap voltage generator generating a stable voltage reference on an output node, comprising a current mirror coupled between the output node and ground, a feedback line including a conducting feedback transistor coupled to an output branch of the current mirror, cooperating with a biasing transistor of the current mirror for keeping constant the collector or drain voltage of the output transistor of the current mirror, and dimensioned such to have the same base-emitter or gate-source voltage of the diode-connected input transistor of the current mirror, a current generator for biasing the feedback transistor by injecting a current into a bias node of the feedback line, and a noise filtering capacitor connected between the bias node and ground, substantially consists in forcing a certain current through the feedback transistor and increasing the resistance of the portion of feedback line in parallel to the capacitor. <??>This method is implemented in a bandgap voltage generator the feedback line of which comprises circuit means connected between the bias node and the feedback transistor for contributing to force a certain current through the feedback transistor and increasing the resistance of the portion of feedback line in parallel to the capacitor. <IMAGE>