A high-order curvature compensation technique for bandgap voltage reference using subthreshold MOSFETs

A bandgap voltage reference with high-order curvature compensation is presented in this study. It exploits subtraction and derivative equalisation of currents generated from two complementary NMOS and PMOS bandgap references (BGRs) using subthreshold MOSFETs. By equating the derivative with respect to temperature of the two currents, generated by the complementary bandgaps, and subtracting these currents, an accurate high-order curvature compensation is achieved. To overcome problems due to the limited input common-mode range of opamps used in BGRs, a transimpedance amplifier with new accurate current compensation that tracks the temperature variation is proposed. This bandgap is implemented using the 0.18m CMOS process with a supply voltage as low as 0.7V. At 0.8V power supply and an output reference voltage of 386mV, the proposed circuit achieves a temperature coefficient of 19ppm/degrees C from 0 to 130 degrees C. The power consumption is 119W and the power supply reduction ratio is 24dB at 1kHz.