A hybrid DC/DC converter for ultra-low power wireless sensor nodes

This paper presents an innovative switched capacitor voltage regulator dedicated to ultra-low power wireless sensor nodes. The regulator supports most of the different power supplies used to power such sensor nodes. Using a linear regulator in parallel improves the dynamic response compared to state-of-the-art switched capacitor regulators. Measuring the load current allows adapting the oscillator frequency and thus keeping the efficiency high for different load currents. To measure the input voltage to select the appropriate operating modes of the regulator a new voltage sensor is implemented. The input voltage range is between 1.35 V and 3.3 V. The regulator is implemented in an Infineon 0.13 μm CMOS process and shows a measured peak efficiency of 56%at an output voltage of 0.8 V and a load current of 1 μA.