A high-efficiency synchronous boost converter with near-threshold self-starting is proposed. It adopts a novel phased start-up method to achieve self-start when the input voltage is below the threshold voltage of the MOS device and without external auxiliary measures. This boost converter is fabricated in a 0.18 um COMS process with a 1.24 × 0.78 um 2 chip area, and can achieve a reliable self-start when the input voltage is below the threshold voltage of 40 mV. It has an input voltage range of 0.7–5 V, a load current range of 0–300 mA, a stable output voltage of 5 V, and a maximum peak efficiency of 95.01%.

Wearable devices require power management systems to achieve high conversion efficiency over a wide range of load currents. Multi-mode mixed modulation can be used in DCDC converters to achieve high efficiency over a wide load current range. The DCDC boost converter proposed in this paper uses a hybrid modulation of DGM (Deep Green Control Mode), PCMC (Peak current mode control)-PFM (Pulse Frequency Modulation) and PCMC-PWM (Pulse Width Modulation). The converter switches smoothly from PCMC-PFM to PCMC-PWM mode under load-current-based conditions and without any mode selection module. The proposed DCDC boost converter is fabricated in a 0.18 μm CMOS process with a Die area of 1.24 × 0.78 μm2. The input voltage range is 0.8–5 V, the output voltage is 5 V, and the load current range is 5–300 mA. Experimental results show that the boost converter can achieve 94.7% peak efficiency. Efficiency of more than 90% can be achieved in the load current range of 30–300 mA.