在虛擬波跟蹤技術可以減少使用低等效串聯電阻的傳統固定導通時間控制降壓轉換器產生的直流偏移電壓量，用於改善輸出電壓的精準值。此外這種技術在負載變化時消除了輸出電壓與電感電流之間相反的趨勢來達到快速的暫態響應，並且在負載由輕載到重載和重載到輕載時分別延長了導通時間和非導通時間。不幸的是，當降壓轉換器操作在不連續導通模式時，隨著電感電流的上升，大幅度地增加電感的消耗以及導通的消耗盡而降低輕載的效率。在本論文中提出了改善輕載效率波追蹤型固定導通時間的降壓電源轉換器，輕載效率可以從52.7%提升到70.12%。

Constant-on-time (COT) control with an extra current feedback in convertional buck converter has the disadvantage is output regulation accuracy is greatly deteriorated by its DC offset voltage, and the opposite of reaction between ouput voltage and extra current current feedback signal deteriorates transient response. In wave tracking technique in constant on time (COT) control DC-DC buck converter has been reducing load-dependent DC offset voltage for load regulation, and also improves instantly opposite reaction between ouput voltage and inductor current. Unfortunately, the disadvantage for this technique is poor power efficiency at light load. This dissertation presents a high light-load efficiency wave tracking control buck converter with inductor current detector. The power efficiency gets greatly improvement from 52.7% to 70.12%.

Contents
摘 要 i
ABSTRACT ii
誌 謝 iii
Contents iv
Figure Captions vi
Table Captions viii
Chapter 1 Introduction 1
1.1 Power Management System 1
1.2 Classification of Voltage Regulators 2
1.2.1 Linear Regulator 2
1.2.2 Charge Pump 3
1.2.3 Switching Regulator 4
1.2.4 Comparison 6
Chapter 2 Basic Knowledge of Ripple-Based Control 7
2.1 Topology of Voltage-Ripple-based Control 7
2.1.1 Hysteretic Control 8
2.1.2 Constant On-time Control 10
2.1.3 Constant Off-time Control 11
2.1.4 Comparison 13
2.2 Motivation and Thesis Organization 15
Chapter 3 Stability Criteria of Constant On-Time buck converter and previous technique 16
3.1 The criteria of Stability in Conventional Constant On-Time Control 16
3.2 Additional Ramp in Constant On-Time Control 18
3.3 Additional Current Feedback Path in Constant On-Time Control 20
Chapter 4 The Issues of Additional Current Feedback Path and Previous Technique 23
4.1 Analyzes ACFP Output Voltage Inaccuracy Issue and Transient Response 23
4.1.1 Analysis of DC Offset in Additional Current Feedback Path 23
4.1.2 Analysis of transient response in Additional Current Feedback Path 27
4.2 Wave Tracking Technique for DC Offset Cancellation 28
4.3 Wave Tracking Technique For Transient Enhancement 30
4.4 Analysis of Power Loss and Efficiency in DC-DC buck converter 33
4.4.1 Quiescent Loss 33
4.4.2 MOSFET Switching Loss 34
4.4.3 MOSFET Conduction Loss 35
4.4.4 Inductor Conduction Loss 35
4.4.5 Efficiency 36
4.5 Proposed Inductor Current Clamper at Light-Load 37
Chapter 5 Circuit implementation 40
5.1 The Current Clamper for Limiting Inductor Current 40
Chapter 6 Simulation Result 42
6.1 Specification 42
6.2 Steady-State and Inductor Current Clamper 43
6.3 Power Efficiency 45
6.4 Comparison with Other Techniques 46
Chapter 7 Conclusion and Future work 47
7.1 Conclusion 47
7.2 Future work 47

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