A 9.1mW All-5V-CMOS Series-Capacitor AC-DC Converter with C_F Reallocation Operations for 85-230V_RMS Mains Achieving 85.6% Efficiency at 858mW/cm³ Density

This work presents an efficient switched-capacitor (SC) AC-DC converter for IoT systems powered by mains in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$120 V_{\text{RMS}}/230 V_{\text{RMS}}$</tex> standards. To eliminate using high-voltage (HV) silicon devices to preserve conversion efficiency and reduce cost, we propose a series-capacitor single-stage AC-DC structure with a fine-grained SC pre-regulation network and active source detaching function, which achieves rectifier conduction loss reduction, output conduction duty extension, and output ripple reduction. At the same, the pre-regulation flying capacitors <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(C_{\mathrm{F}})$</tex> can be reallocated to be in parallel to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$C_{\text{OUT}}$</tex> dynamically according to load conditions, further improving the output ripple and enhancing total capacitance utilization. Fabricated in a 180-nm process using all 5-V CMOS transistors, the converter supplies an output <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(V_{\text{OUT}})$</tex> of 2.6~5V from an <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$85\sim 230V_{\text{RMS}}$</tex> input <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(V_{\text{IN}})$</tex>. It outputs a maximum power of 9.11mW with 85.6% efficiency and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$858\text{mW}/\text{cm}^{3}$</tex> overall system power density.