A Two-Step Self-Startup Hybrid Structure Step-Up Converter Using Standard 5P0 MOSFETs Achieving 36 × Voltage Boosting With 50 mV Input Voltage and 84 × Input Voltage Range for Self-Powered IoT Applications

This article presents a hybrid structure step-up converter to achieve self-startup at ultralow input voltage and very wide input voltage range. To realize self-startup, a two-step self-startup strategy is designed, which involves three periods (charge pump self-startup period, hybrid mode period, and boost operating period). To further reduce the self-startup voltage and promote driving capability, a multistage multiphase charge pump with body-bias controlled ring oscillator is proposed. By optimizing design of the ring oscillator, the output ripple of the charge pump is reduced significantly. To solve the inherent contradiction between body-bias technique and operating voltage range, current limitation technique is adopted. The converter is fabricated by using standard 180 nm 5P0 CMOS process with 4.8 mm
²
chip area. Measurement results show that the converter can kick-start at 440 mV input voltage, and provide over 96.35 mW at 300 mV input voltage. The input voltage range is up to 84× (50 mV–4.2 V). The output voltage can be maintained at 1.8 V with the minimum input voltage of 50 mV, where 36× voltage step-up ratio is obtained. The maximum inductor current reaches 2 A, and the peak power conversion efficiency of 95.6% is achieved.