A digital compensation technique for a current reference in an ultra-wide temperature range

A new digital calibration technique to compensate the process and temperature induced deviation of current reference is presented. The circuit is designed with 0.18-μm CMOS all-digital technology. Temperature and process compensation is achieved by a Digital Calibration (DC) module in which binary search is adopted to accelerate the calibration. The DC dynamically adjusts the digital-controlled resistor array, which is used to regulate the output bias current. No matter how the temperature changes in an ultra-wide ranging from -95°C to 140°C, the output current can be calibrated to 100 μA with a maximum error of 0.3 μA under all the process corners. The same precision can also be obtained when the load voltage is changed from 0.31 V to 1.04 V, and the load sensitivity is about 8000 ppm/V. The digital part consumes little static power and the analog calibration part can be turned off after the calibration is finished, as a result, the power consumption is only 100 μA.