A 2.56ppm/°C High-Order Curvature-Compensated Bandgap Reference Utilizing Four-Input Current Feedback Amplifier

This paper presents a high-order curvature-compensated bandgap reference (BGR) that utilizes a four-input current feedback amplifier. High-order curvature compensation terms (T∙ ln(T) dependence) are produced by the VEB’s difference of bipolar transistors (BJT) whose currents are biased at proportional to absolute temperature (PTAT) and complementary to absolute temperature (CTAT) currents, which can diminish the temperature-dependent nonlinearity of traditional BGR. A four-input current feedback summation amplifier innovatively incorporates an additional input pair to complete the summation of the first-order and high-order curvature compensation terms. In conjunction with an auto-zero technique built on a new timing constraint, the proposed BGR enhances the accuracy as well as suppresses the low-frequency noise. Implemented in a standard 180-nm CMOS process, this work exhibits a minimum temperature coefficient (TC) of 2.56 ppm/∘C and an average TC of 3.5 ppm/∘C, with a worst-case scenario of 5.08 ppm/∘C from -40∘C to 125∘C, requiring a mere one-point, 4-bit trimming. Measurement results indicate an initial 3σ inaccuracy of ±0.14% without trimming, which is reduced to ±0.05% with trimming. The low-frequency noise (0.01Hz to 10Hz) is 6.8 μVRMS.