A 58 nW ± 35 ppm/°C Oscillator for IoT Battery-less Sensor Applications

We present in this paper a battery-less sensor structure with energy harvesting in which an antenna is used for both collecting the RF signals and as a sensing element. Also, an ultra-low-power oscillator with low sensitivity to temperature variations has been designed to generate a clock signal for the proper operation of the proposed sensor design. This oscillator is intended for ultra-low power and low-frequency applications. It consumes only 58 nW of power from a 1 V supply while occupying 190 μm x 120 μm of silicon area. In addition, it shows temperature sensitivity of ± 35 ppm/°C over temperatures ranging from −40 to 85 °C. The proposed structure has been designed and simulated with a 0.18 μm standard CMOS technology. The proper functionality of the presented design has been validated through post-layout simulation results.