Patent ID: 7714563

Claim:
A bandgap reference circuit including an amplifier having an inverting and a non-inverting input and providing at its output a voltage reference, the circuit including: a. a first pair of transistors, the first pair including a first and second transistor of the circuit, the first transistor being coupled to the non-inverting input of the amplifier, the bases of the first and second transistors being commonly coupled, the first transistor being additionally coupled to the amplifier output via a feedback resistor, the second transistor being provided in a diode configuration, b. a second pair of transistors, the second pair including a third and fourth transistor of the circuit, the third transistor being coupled to the inverting input of the amplifier, the emitters of the third and fourth transistors being coupled to ground via a reference resistor, the fourth transistor being provided in a diode configuration and being coupled via a coupling resistor to the second transistor, and wherein the base of the third transistor is coupled to the commonly coupled first and second transistors, the collector of the third transistor being coupled to the collector of the first transistor such that the first and third transistors form a preamplifier to the amplifier, and further wherein the emitter areas of the first and fourth transistors are scaled to be larger than that the emitter areas of the second and third transistors such that two base-emitter voltage differences, of the form of proportional to absolute temperature (PTAT) voltages, are developed across the coupling and feedback resistors respectively, the resultant PTAT currents generating a PTAT voltage across the reference resistor, this PTAT voltage in combination with the base emitter voltages of the combined second and third transistors being reflected at the output of the amplifier as a first order temperature insensitive voltage, and further wherein the circuit includes a filter provided between the non-inverting input and ground to minimize high band noise contributions to said temperature insensitive voltage, the circuit further including: a current shunt provided to shunt at least a portion of the feedback current away from the first transistor so as to effect a reduction in the collector and base currents of the first and third transistors thereby reducing low band noise contributions to said temperature insensitive voltage.