A 46 nW Power Management Unit with Battery Extender for Solar Energy Harvesters Using 0.18 μm CMOS

This work presents the design of an ultra low power (ULP) management unit to be used in conjunction with tiny solar energy harvesters (EH) providing very low power for energy autonomy in wireless sensor applications. The power management unit (PMU) is designed using 0.18 μm CMOS in subthreshold region of MOSFET for reduced power consumption and increased efficiency. A battery extender module is also implemented to obtain continuous power in the absence of energy harvesting source. The PMU achieves a maximum of 72.3% efficiency and has a response time of 5.8088 s and 13.03 ms at the input voltages of 0.98 and 1.33 V, regulating the output voltage at 0.95 V and 0.968 V, respectively. The proposed PMU consumes 46 nW and 68 nW along with the battery extender, at input voltages of 0.98 V and 1.33 V, respectively, thereby making it suitable for ultra low voltage and low power applications.