An RFID-Based Self-Biased 40 nm Low Power LDO Regulator for IoT Applications

There are emerging applications, like bridge structural health monitoring, continuous patient condition and outdoor aiding of the elderly and the disabled, where Internet of things (IoT) nodes are used with very limited accessibility and no connection to the main supply network. They may also be exposed to harsh environmental conditions. These are applications where power and available area constraints are of great concern. In this paper, we design a 1.1 V low dropout (LDO) linear regulator in 40 $\mathrm{n}\mathrm{m}$ technology to be embedded in IoT nodes. To address these constraints, we used state-of-the-art, variability-aware resistor-less sub-threshold biased CMOS-only ultra low power consumption configurations having low active area. The proposed LDO is internally compensated with embedded 18 $\mathrm{p}\mathrm{F}$ Miller and 10 $\mathrm{p}\mathrm{F}$ load capacitances. It can supply 1 $\mathrm{m}\mathrm{A}$ maximum load current with 0.8 uA quiescent current. The dropout voltage of the regulator is 200 $\mathrm{m}\mathrm{V}$ with minimum input voltage of 1.3 V. The efficiency of the regulator is 84%, which is about 99% of the maximum achievable efficiency for a 200 $\mathrm{m}\mathrm{V}$ dropout voltage. The whole circuit, consisting of the embedded voltage reference and the Miller and load capacitances, takes less than 0.007 $\mathrm{m}{\mathrm{m}}^2$ of the die size with 1 μ$\mathrm{W}$ power consumption.