A high-precision ultra-low-power hysteretic voltage detector for energy harvesting system
A high-precision ultra-low-power, hysteretic voltage detector (HVD) featuring temperature and process insensitivity is presented in this paper. In order to improve its thermal stability, a temperature-independent current is generated by a special voltage-controlled current source. The current is compared with a reference current to determine the start-up voltage of hysteresis window. And a Schmitt inverter is served to provide the hysteresis window. Besides, a current pre-amplifier is developed to enhance the HVD's response to small changes of the detected voltage. The HVD is designed and fabricated in SMIC 0.18 μm CMOS process. The simulation results show that its hysteresis window is about 0.02V. And the sensitivity to temperature and process corners are about 347ppm/°C and -1.5%~2.3% respectively. In addition, the HVD can response precisely to as low as 1mV variation around the switching voltage. The total power consumption of this HVD is only 840nW at 1.8V supply voltage.