Patent ID: RE39918

Claim:
A direct current sum bandgap voltage comparator comprising: a summing node; a plurality of current sources connected to the summing node, each current source further comprising at least one transistor, and each current source supplying a current to the summing node and being connected to a power supply voltage, wherein the currents sources supply currents according to a bandgap equation: K 1 (V CC −V T )+K 1 V T =K 2 V BE +K 3 (kT/q) where V CC is the power supply voltage, V T is a predetermined threshold voltage of a transistor in a first current source within the plurality of current sources, V BE is a base emitter voltage of a transistor in a second current source within the plurality of current sources, k is Boltzman's constant, T is a temperature in kelvin of a transistor in a third current source within the plurality of current sources, q is an electronic charge constant, and K 1 , K 2 , and K 3 are constants determined by a resistance and a transistor length in the first, second, and third current sources, respectively; and an indicator circuit having an input connected to the summing node and generating a logical signal at an output, responsive to voltage changes in the summing node.