Patent ID: 8390363

Claim:
A temperature compensation circuit for generating a temperature compensating reference voltage (V REF ) used to compensate for temperature drift of a metal resistor comprising: a Bandgap reference circuit configured to generate a Bandgap reference voltage (V BGR ) that is substantially temperature independent and a proportional-to-absolute-temperature reference voltage (V PTAT ) that varies substantially in proportion to absolute temperature; an operational amplifier that is connected to the Bandgap reference circuit and that has an output on which V REF is based; and a feedback circuit that is connected to the operational amplifier and to the Bandgap reference circuit and that is configured so as to cause V REF to be substantially equal to V PTAT times a constant k 1 , minus V BGR times a constant k 2 , and wherein at least one of the following: the feedback circuit includes a string of resistors having two ends and a node between two resistors in the string; the constant k 2 is a function of the resistances of the resistors in the string; the feedback circuit has a trimming device configured to allow the ratio of the two resistors to be adjusted; the ratio of the resistors in the string has been adjusted so as to maximize the ability of V REF to compensate for variations in the resistance of a particular metal resistor on a particular semiconductor chip as a function of temperature; and the Bandgap reference circuit includes a PN junction connected to a string of resistors having a node between two resistors in the string and wherein the non-inverting input of the opamp is connected to the node; the Bandgap reference circuit is of the Brokaw type; the feedback circuit includes a switched capacitor circuit; or the Bandgap reference circuit is configured to stack a base-to-emitter voltage on top of a V PTAT voltage to generate a bandgap reference voltage V BGR a non-inverting input of the operational amplifier is coupled to a V PTAT voltage, the feedback circuit is coupled to V BGR and the output of the operational amplifier, the feedback circuit is configured to develop a weighted average voltage of V BGR and the output of the operational amplifier and an inverting input of the operational amplifier is coupled to the weighted average voltage.