An Efficient Zero Current Switching Control for L-Based DC–DC Converters in TEG Applications

This brief presents an improved zero current switching (ZCS) control for a high-gain inductor-based dc–dc converter targeting thermoelectric generator for wearable electronics. The proposed ZCS control is an all-digital circuit that utilizes a simple finite state machine and a 3-bit counter to locate the zero current point. In addition, an efficient push–pull circuit along with delay capacitance banks is used to tune the delay near the zero current point to reduce the estimated error. The proposed control circuit achieves 56 delay steps using 3 control bits while having a high resolution, which helps in maintaining the efficiency of the converter. The prototype chip is fabricated in 65-nm CMOS and occupies an area of less than 0.04 mm ². The measured results of the converter confirm 81% peak efficiency at 55- <inline-formula> <tex-math notation="LaTeX">$\mu\text{W}$</tex-math></inline-formula> output power and 50-mV input voltage.