A sub-µW bandgap reference circuit with an inherent curvature-compensation property

A new current-mode bandgap reference circuit (BGR) which is capable of generating sub-1-V output voltage is presented. It has not only the lowest theoretical minimum current consumption among published current-mode BGRs, but also additional advantages of an inherent curvature-compensation function and not requiring NPN BJTs. The curvature-compensation is achieved by utilizing the exponential behavior of sub-threshold CMOS transistors to compensate the BJT base-emitter voltage high-order temperature dependence. By taking advantages of the continuing development of CMOS technology, sub-µW power consumption is achieved with a reasonable core area. Related design considerations and challenges are discussed and analyzed. The proposed BGR is realized in a TSMC 90 nm process. Measurement results shows a temperature coefficient without trimming as low as 10.1 ppm/°C over a temperature range of 70°C because of the proposed curvature-compensation technique. The average value is 32.6 ppm/°C which could be improved by trimming resistor ratios. The average power consumption at room temperature is 576 nW, with a core area of only 0.028 mm².