A 1-nA 4.5-nW 289-ppm/°C Current Reference Using Automatic Calibration

This article proposes an ultralow-power accurate current reference that generates 1-nA current. Since an automatic calibration circuit periodically calibrates the generated current of the current reference, the current reference is able to achieve ultralow power consumption and high accuracy simultaneously without employing a multiple temperature trimming. Prototype chips are fabricated in a 180-nm CMOS technology and are tested with a field programmable gate array (FPGA) board that controls the timing of the calibration. When the calibration is activated every 25 min, measurement results show that the current reference achieves a temperature coefficient of 289 ppm/°C and a line sensitivity of 1.4%/V with no help from a multiple temperature trimming. Estimated total power consumption is 4.5 nW at 23 °C, including the power consumption of a wake-up timer.