Startup Techniques for 95 mV Step-Up Converter by Capacitor Pass-On Scheme and ${\rm V}_{\rm TH}$ -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 (V_TH) trimming is applied to reduce the minimum operating voltage (V_DDMIN) of the oscillator. Experimental results demonstrate the 34% V_DDMIN reduction of the oscillator by post-fabrication V_TH trimming. The proposed step-up converter achieves the lowest startup voltage in standard CMOS without using a mechanical switch or large transformer.