A Bootstrapless KY-S-Hybrid Buck-Boost Converter with Full Range iLs Reduction and 400% Line Transient Response Acceleration for AI-Mobile Application

In this paper a novel bootstrapless hybrid buck-boost dc-dc converter for AI-mobile application is proposed. It leverages KY-boost converter combining with S-hybrid converter to achieve full voltage-conversion-ratio (VCR) inductor current stress reduction. As a result, 6.8 uH 0805 small form factor inductor could be employed. Moreover, a bootstrapless driving strategy is introduced to make sure full NMOS power switches adopted with small on-chip area and 0 off-chip bootstrap capacitors. On the other hand, nowadays, the AI-mobile application is facing stringent line transient challenges on the buck-boost converter. This paper leverages a line transient feedforward technique to reduce the line to output perturbation up to 400% compared to the conventional control V-mode algorithm. Simulated in a 180 nm CMOS process, this design achieved 95.5% peak efficiency at V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IN</inf> = 4.2 V to V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</inf> = 3.3 V.