A 3.5 ppm/°C Novel Curvature-Compensated Bandgap Reference Using Four-Input Current Feedback Amplifier with 3σ Inaccuracy of ±0.05%

A novel curvature-compensated bandgap reference (BGR) using a four-input current feedback amplifier is presented in this paper. High-order curvature compensation terms (T•ln(T) dependence) are produced by the VBE’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. Combined with an auto-zero technique built on a new timing constraint, the proposed BGR greatly enhances the BGR’s accuracy and suppresses the low-frequency noise. Implemented in a standard 180nm CMOS process, the proposed BGR achieves the average temperature coefficient (TC) of 3.5 ppm/°C and the worst case is 5.08 ppm/°C from -40 °C to 125 °C with merely one-point 4-bit trimming. Measurement shows a 3σ initial inaccuracy of ±0.14% without trimming, and ±0.05% is achieved with trimming. The low-frequency noise (0.01Hz to 10Hz) is 6.8 µVRMS.