臺灣博碩士論文加值系統

本論文的目的是設計出一個新的截止時間控制電路並將它運用在直流直流降壓轉換器，本論文提出的截止時間控制電路可以讓直流直流降壓轉換器在寬輸入電壓範圍皆可以得到較低的切換頻率，藉此降低系統的切換損耗以得到較高的效率。另外在固定輸入電壓的情形針對不同的負載時，也採用了雙模式設計。當電路處於重載時，電路會操作於連續導通模式。當電路處於輕載時，會使用波谷切換技術使電路會持續操作在邊界導通模式而不會進入不連續導通模式，透過降低切換時功率電晶體的跨壓以降低輕載操作時的切換損失。
本次設計的控制晶片是採用TSMC 0.35μm 2P4M CMOS製程，晶片面積為2.174mm2，搭配外加的功率電晶體和被動元件，建構出一個非同步降壓轉換器。本系統的輸入電壓範圍為4.5V~5.4V，輸出電壓為1.8V，輸出電流範圍為0A至1A。根據量測結果，在連續導通模式下，可以在寬輸入電壓範圍達到0.33%效率的提升。在邊界導通模式下，相較於不連續導通模式也可以達到0.25%效率的提升。

The purpose of this thesis is to design a new off-time control method and apply it to a DC-DC buck converter. The off-time controlled circuit proposed in this thesis can make the DC-DC buck converter get the lower switching frequency for wide input voltage range. Thereby reducing the switching loss of the system to achieve higher efficiency. In addition, when the input voltage is fixed for different loads, a dual-mode design is also adopted. When the circuit is under heavy load, the circuit operates in continuous-conduction mode. When the circuit is under light load, valley switching technique is used to keep the circuit in boundary-conduction mode without entering discontinuous-conduction mode. The switching loss at light load is reduced by reducing the voltage across the power transistor during switching.
The proposed chip is fabricated using TSMC 0.35μm 2P4M CMOS process with an area of 2.174mm2. With an additional power transistor and passive components, an asynchronous buck converter is constructed. The input voltage range is from 4.5V to 5.4V. The output voltage is 1.8V. The load current range is from 0 to 1A. According to the measurement results, in the continuous-conduction mode, the efficiency can be improved by 0.33% for wide input voltage range. In the boundary-conduction mode, an efficiency improvement of 0.25% can be achieved compared to the discontinuous-conduction mode.

口試委員會審定書 #
誌謝 I
摘要 III
Abstract V
Contents VII
List of Figures IX
List of Tables XXI
Chapter 1 Introduction 1
1.1 Motivation 1
1.2 Thesis Organization 3
Chapter 2 Buck Converter Principle 5
2.1 Basic of Buck Converter 5
2.2 Efficiency of Buck Converter 10
2.3 Control Methods of Buck Converter 14
2.3.1 Voltage-mode Buck Converter 14
2.3.2 Current-mode Buck Converter 16
2.3.3 On-time Controlled Buck Converter 18
2.3.4 Off-time Controlled Buck Converter 20
2.3.5 Method Comparison 21
Chapter 3 Dual-mode Buck Converter 23
3.1 Proposed Off-time Generator 24
3.2 Dual-mode Control 29
3.3 Peak-current Mode Control 36
Chapter 4 Circuit Implementations 39
4.1 Specification 39
4.2 Component Design 41
4.3 Simulation Results 49
4.4 Layout 67
4.5 Die Photo 67
Chapter 5 Measurement Results 69
5.1 Experimental Waveforms 70
5.2 Experimental Data 95
5.3 Result Analysis 104
5.4 Comparison 106
Chapter 6 Conclusions and Prospect 109
6.1 Conclusions 109
6.2 Prospect 110
Reference 113

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