Novel low-power 12-bit SAR ADC for RFID tags

A novel design and measuring results of an ultra-low power 12bit Successive-Approximation ADC for autonomous multi-sensor systems are presented. The comparator and the DAC are optimised for the lowest power consumption. The proposed design has a power consumption of 0.52µW at a bitclock of 50-kHz and of 0.85µW at 100-kHz with a 1.2-V supply. The Figure-of-Merit reached with such implementation is of 66 fJ/conversion-step. The ADC was realised in the NXP CMOS 0.14µm technology with an area of 0.35 mm2. Only four metal layers were used in order to allow 3D integration of the sensors.