An 85-mV input, 50-µs startup fully integrated voltage multiplier with passive clock boost using on-chip transformers for energy harvesting

A fully integrated voltage multiplier with low startup voltage (V_START) and fast startup is developed for the energy harvesting (e.g. thermoelectric energy harvester). The generation of the high frequency clock signal with large amplitude without using off-chip components is a key to achieve the voltage multiplier. The proposed passive clock boost using two on-chip transformers with the winding turns ratio of three reduces V_START. The 138-MHz clock generation with a fully integrated LC oscillator enables the fast startup. The voltage multiplier fabricated in 65-nm CMOS achieves the lowest cold V_START of 85mV in the published fully integrated voltage multiplier and the shortest startup time of 50μs.