(A) high-speed high-efficiency 1-W DC-DC converter with on-chip power MOSFET

Abstract

The most outstanding features for portable electronic systems are compact size, light weight, long battery life, high quality, and so on. The most important building block that influences to these features is DC-DC converter, and high-speed, high-efficiency power circuit and sub-block design techniques are inevitable. In this thesis, a high-speed high-efficiency 1-W DC-DC converter with on-chip power MOSFET is designed. A 3.7V Automatic Loop Bandwidth (ALB) controlled Quasi-PWM (QPWM) boost converter from two 1.5V Ni-MH batteries is proposed. And a 1.8V variable dead time controlled gate driver IC in buck converter from 3.7V lithium-ion battery is proposed as well. These two converters are fabricated using Hynix/MagnaChip $0.35\mu m$ 2-poly 4-metal standard CMOS process. The proposed QPWM control provides advantages of both accurate PWM control and fast hysteresis control. In addition, an Automatic Loop Bandwidth (ALB) control makes it possible for the output voltage to return to its original value quickly during transient. The test results show that output voltage took only 0.5ms to return to its expected value when 0.3A current step in load current. It takes about 11ms in conventional PWM control. The maximum efficiency is 94%, the minimum efficiency is 80%, and 1.5W power can be provided to the maximum. 1MHz switching frequency is used, but it can operate over than 2MHz In the proposed variable dead time controlled gate driver, the load current variation is sensed and reflected to the dead time variation. In ideal operation, zero dead time at switch output terminal is required, so the duty input at switch gate terminal is controlled to be shifted. The voltage and current peak can be minimized, which results a decrease in switching loss and good EMI performance. The maximum efficiency is 95%, the minimum efficiency is 78%, and 2W power can be provided to the maximum. 1MHz switching frequency is used, but it can operate over than 4MHz.