University of California

Navitas Semiconductor Limited

Jun Li

Xiaoru Chen

Ying Chih Chang

Milind Gupta

Chih-Hsien Hsieh

A power factor correction circuit for a boost converter comprises a voltage converting means and a voltage-to-time converting means. The voltage converting means converts a supply voltage based on a time period of a turn-on duration Tand a turn-off duration Tof the boost converter into an output voltage. The voltage-to-time converting means generates the turn-on duration Tbased on the output voltage from the voltage converting means. The power factor correction circuit adjusts the turn-on duration Tsubstantially in accordance with the following relationship: The first parameter includes at least one first process-dependent parameter and the second parameter includes at least one second process-dependent parameter. The first process-dependent parameter and the second process-dependent parameter are same electrical characteristic associated with different circuit components in the power factor correction circuit.

Power factor correction circuit for a boost converter

Nitroxide mediated free radical polymerization of vaporized vinyl monomers, including acrylic acid (AAc), styrene (St), N-2-(hydroxypropyl)methacrylamide (HPMA) and N-isopropyl acrylamide (NIPAAm), on silicon wafers is demonstrated. FTIR, ellipsometry and contact angle goniometry were used to characterize the chemical structures, thickness and hydrophilicity of the films. The growth of film is linearly proportional to its reaction time, leading to the easy and exact control of polymer film thickness from nanometers to submicrons. The capability of polymerizing various monomers allows us to fabricate various functional polymer brushes. The reversible thermo-responsiveness of a 200 nm thick grafted poly(NIPAAm) film in aqueous solution is demonstrated with over 50% change in thickness at its lower critical solution temperature. A tri-block copolymer of poly(AAc)-b-polySt-b-poly(HPMA) is successfully synthesized, proving the renewability of TEMPO-mediated polymerization at vapor phase. Surface polymer composition and morphology is thus controlled at nanoscale by utilizing vapor phase surface-initiated controlled polymerization.

Synthesis of functional polymers and block copolymers on silicon oxide surfaces by nitroxide-mediated living free radical polymerization in vapor phase

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Irvine, CA, United States of America

Jun Li