Low cost curvature correction of bandgap references for integrated sensors

Due to increasing demands on the accuracy of integrated sensors, it is very important to improve the accuracy of bandgap voltage references. Since the second order non linearity of the function VBE(T) is generally the main limit to the accuracy of calibrated bandgap voltage references, several methods for the curvature-correction of VBE(T) have been reported in literature; unfortunately these methods require quite complex circuitry. In this paper we investigate a low cost curvature correction method, consisting in taking advantage of the temperature dependence of integrated resistors and in using PTAT/R collector currents; furthermore we introduce two new circuit topologies which permit to take full advantage of this approach in spite of technological limitations.