Patent ID: 7550958

Claim:
A bandgap voltage generating device, for generating a bandgap voltage to a node coupled to a core circuit, the bandgap voltage generating device comprising: a first bandgap voltage regulator, coupled to the node, for generating a first bandgap voltage to the node; a second bandgap voltage regulator, coupled to the core circuit, for generating a second bandgap voltage to the node, wherein the power consumption of the second bandgap voltage is less than the power consumption of the first bandgap voltage regulator; and a controller, coupled to the first bandgap voltage regulator and the second voltage regulator, for controlling the first bandgap voltage regulator and the second bandgap voltage regulator according to a mode of the core circuit; wherein when the core circuit is operated in an standby mode, the first bandgap voltage regulator is disabled by the controller and the core circuit is powered by the second bandgap voltage regulator; and when the core circuit is operated in an active mode, the first bandgap voltage regulator is enabled by the controller and the core circuit is powered by at least the first bandgap voltage regulator.