Switched-capacitor boost converter design and modeling for indoor optical energy harvesting with integrated photodiodes

Integrated photovoltaic energy harvesting from indoor lighting is appropriate for ultra-low duty cycle applications. Indoor illumination may flicker due to AC mains rectification or pulse-width-modulated dimming, causing ripple on the output voltage. Switched-capacitor DC/DC conversion can increase harvester output voltage and reduce this ripple. We present a switched-capacitor boost converter design, a model that matches measured output voltage within 10% for 500 Hz to 5 MHz switching frequencies, and compare the converter to a series photodiode configuration. The distortion caused by supply ripple on a passive filter delta-sigma modulator is modeled and verified with measurements from a 180nm test chip.