The design of low-noise bandgap references

The noise power of bandgap references is directly related to the current consumption of the bandgap reference. This paper describes the design of low-noise bandgap references. It is shown that for an idealized bandgap reference, a fundamental noise limit exists when the limited current consumption is a constraint. A design example is given of a 1 V bipolar bandgap reference with a current consumption of 5 mu A. The output voltage is 200 mV and the mean temperature dependency is approximate to 20 ppm/K for 0 degrees C to 100 degrees C. The output noise density equals 166 nV/root Hz.