Startup Techniques for 95 mV Step-Up Converter by Capacitor Pass-On Scheme and VTH-Tuned Oscillator With Fixed Charge Programming

This paper presents a 95 mV startup-voltage step-up DC-DC converter for energy harvesting applications. The capacitor pass-on scheme enables operation of the system from an input voltage of 95 mV without using additional off-chip components. To compensate for the die-to-die process variation, post-fabrication threshold voltage (VTH) trimming is applied to reduce the minimum operating voltage (VDDMIN) of the oscillator. Experimental results demonstrate the 34% VDDMINreduction of the oscillator by post-fabrication VTHtrimming. The proposed step-up converter achieves the lowest startup voltage in standard CMOS without using a mechanical switch or large transformer.