High-Efficiency PFM Boost Converter With an Accurate Zero Current Detector

In this brief, an integrated pulse-frequency modulation boost converter with an accurate zero current detector (ZCD) is presented. The proposed ZCD is used to improve the power efficiency of the boost converter and comprises two hysteresis comparators, the transistors MZ1-MZ3, and a set-reset latch to eliminate the reverse current of the high-side switch in the energy release period. This ZCD can also avoid early or delayed detection and ensure stable operation in the discontinuous conduction mode. Furthermore, a new comparator incorporating an appropriate logic gate is developed to eliminate a constant current during the energy storage period. The proposed boost converter was designed and fabricated using the standard TSMC 0.18-μm 1P6M CMOS technology with a chip area of 0.43 mm2. The experimental results revealed that the maximum power efficiency of 88.39% is achieved at a load current of 50 mA, and the lightload efficiency is enhanced by the proposed ZCD. Furthermore, power efficiency of the boost converter with the proposed ZCD is 28.29% higher than that of the existing ZCD design at a load current of 1 mA.