Fast-Response Buck Converters with Current-Mode and Fixed-Frequency Hysteretic Control

Abstract

This thesis is about the fixed-frequency fast-transient regulator Based on control methods the thesis can be divided into two parts: The first part focuses on the fast transient current-mode controlled buck converter Through the systematic design procedure and analysis including the system modeling compensator design transistor level design and chip implementation the loop response is improved for better dynamic response The design procedure is verified by the chip’s measurement results The measurement results show that this converter can operate with load current from 200mA to 500mA in a supply voltage from 2 7 to 4 2V and the output voltage of 1 8V The recovery time is about 10us and the highest efficiency is 93% By the frequency domain measurement the stability of proposed buck converter can be guaranteed This converter is designed and fabricated with TSMC 2P4M 0 35μm CMOS process The off chip inductor and the output capacitor are 4 7μH and 10μF In the second part of this thesis a fast transient quasi-V2 fixed-frequency hysteretic buck converter with wide load current range is proposed This converter uses the phase-locked loop through the proposed Two Stage Window Control Circuit to stabilize the switching frequency Under ultra-light load condition this converter operates in PFM mode to reduce the switching loss and improve the light load efficiency By the quasi-V2 technique the inductor current information can be obtained without relying on large ESR of output capacitor to reduce the output ripple This converter has been designed and fabricated by TSMC 2P4M 0 35μm CMOS process The off chip inductor and the output capacitor are 2 2μH and 10uF The measurement results show that this converter can operate with load current from 18mA-700mA in a supply voltage from 3 3-3 9V and the output voltage of 1 2V With the PLL the switching frequency is maintained constant at 1MHz The transient response time is about 5us and the highest efficiency is 95 6%

Date of Award	2014 Jan 24
Original language	English
Supervisor	Chien-Hung Tsai (Supervisor)