A 1μw-to-100μw Output Range Boost DC-DC with Pseudo Open Loop Structure and Power Efficient Ring Oscillator for Wireless Energy Harvesting

This paper proposed a 0.9-to-1.2V output voltage boost DC-DC regulator for wireless energy harvesting of which the power efficiency has been much improved under light load condition utilizing pseudo open loop structure (POLS) and power efficient ring oscillator. The POLS makes the whole system work in the open loop state when the output voltage is stable, so the energy cost for voltage regulating can be saved a lot. The POLS is realized by two hysteresis comparators controlled by a very slow clock, the comparators generate different threshold voltage by a single reference and those different thresholds can lock up the output. The power efficient ring oscillator generates the feedback control frequency ranges from 230Hz-to-220KHz utilizing an 11-bits-binary series capacitor array. Accordingly, a boost DC-DC, which operates in discontinuous-conduction mode (DCM) and regulates voltage by a constant-on-time pulse frequency modulation (PFM), is proposed. As a simulation result, the input voltage ranges from 0.3-to-0.5V and the output voltage ranges from 0.9-to-1.2V while the output load ranges from 1μw-to-100μw, the peak efficiency is 83.7% when the load is 1μw.