A 95% Peak Efficiency Modified KY Converter With Improved Flying Capacitor Charging in DCM for IoT Applications
Caolei Pan, Wen‐Liang Zeng, Chi‐Seng Lam, Sai‐Weng Sin, Chenchang Zhan, Rui P. Martins
Abstract
This article presents a modified KY (M-KY) converter, which provides a continuous flying capacitor charging current in discontinuous conduction mode (DCM), when compared with the conventional KY converter. This modification extends the load current range, improves the power efficiency, and simplifies the zero current detection (ZCD). To meet IoT application requirements, we implement a double clock timing (DCT) control combined with an adaptive sizing technique, which obtains a high efficiency over a wide load range, with a fast load transient response. To reduce the chip size and quiescent current, we also adopt a clocked-feedback resistor network (CFRN). Implemented in standard 65-nm CMOS, the proposed M-KY converter achieves a peak efficiency of 95% and a wide load current ranging from 0.001 to 100 mA (100 000X load range). Under a load transient between <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6~\mu \text{A}$ </tex-math></inline-formula> and 100 mA, the measured recovery time is within a single slow clock cycle of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5~\mu \text{s}$ </tex-math></inline-formula> . The measured minimum quiescent current is 240 nA with an active chip area of 0.15 mm2.