臺灣博碩士論文加值系統

在可攜式電子產品的應用上，高效能和小型的電壓轉換器在提供系統電源上扮演非常重要的角色。為了減少輸出級濾波器的面積，提出高頻切換的直流轉直流降壓轉換器來達到元件整合的功能。然而，對傳統電流控制模式之直流轉直流降壓轉換器來說並不適合在高頻切換的操作，因為使用到運算放大器之子電路其頻寬會被限制住。也就是說，由於電路頻寬的極限造成不正確的操作且無法跟上系統的操作頻率。為了保證電壓轉換器可以操作在高切換頻率下，全電流脈波寬度調變控制器在本論文中被提出了。

由於使用了全電流脈波寬度調變控制器，因為少了外部補償元件使得操作電路將會變的較簡單，且控制訊號全都轉換成電流形式讓訊號相加變得直接。為了能提供高效能電源電壓，也是其中一種電流模式控制技術的全電流脈波寬度調變控制器將可得到較佳的線調節率和負載調節率。

本篇論文實現了20MHz的全電流控制高頻切換直流轉直流降壓式電源轉換器，且以台灣積體電路製造股份有限公司點三五微米互補式金氧製程來實現，輸入電壓範圍從3.0伏特到4.0伏特，其負載調節率及線調節率分別為0.18356mV/mA和48.5V/V。系統特色為可使用較小的外部濾波元件且得到較快的暫態響應，其中電感大小只需200nH、輸出電容值只需5μF。非常適合於可攜式電子產品之電源管理。

For portable electronic device applications, high performance and compact size voltage regulator plays an important role to provide system power. To reduce the size of output filter, a high switching dc-dc buck converter is presented to achieve high integration. However, the conventional current mode DC-DC buck converter is not suitable to high switching design because the sub-circuits, which uses operational amplifier, restrict the bandwidth. That is to say, the limitation of circuit bandwidth causes incorrect operation and can not follow the system switching frequency. To ensure the switching regulator can operate at high switching frequency, the current domain PWM controller is presented in this thesis.

Owing the current domain PWM controller, the circuit implementation becomes simple and there are not any external compensation components. The control signals are transformed to current form to process addition of control signal directly. For providing a high performance supply voltage, the current domain PWM control is one of current-mode technique to get good line and load regulations.

In this thesis, a high switching DC-DC buck converter in current domain control with frequency 20MHz is implemented. The test chip was implemented by TSMC 2P4M 0.25-μm CMOS technology. Input operation range varies from 3.0V to 4.0V. The load regulation and line regulation are 0.18356mV/mA and 48.5mV/V respectively. The system features smaller output filter. That is, the inductor and output capacitor values are only 200nH and 5μF respectively. Fast transition response is achieved and demonstrates the design suitable for power management in the portable devices.

Chapter 1 1
Introduction 1
1.1 Background of Power Management System 1
1.2 Classification of Voltage Regulators 3
1.2.1 Linear Regulator 3
1.2.2 Charge Pump 5
1.2.3 Switching Regulator 6
1.2.4 Comparison 7
1.3 Motivation 8
1.4 Thesis Organization 9

Chapter 2 10
Basic Knowledge of Switching Regulator 10
2.1 Topologies of DC-DC Converter 10
2.2 Technologies of Controlling Modulator 12
2.2.1 Pulse Width Modulation (PWM) 13
2.2.2 Pulse Frequency Modulation (PFM) 14
2.2.3 Hysteretic Control technique 16
2.3 The Theorem of Current Mode Control 18
2.3.1 Operation Principles of Current Mode Buck Switching
Regulator 19
2.3.2 Sub-harmonic Oscillation at Duty Ratio > 0.5 21
2.3.3 Ramp Compensation 23
2.3.4 Continuous Conduction Mode (CCM) and Small Signal
Modeling 25
2.3.5 Discontinuous Conduction Mode (DCM) and Small Signal
Modeling 30
2.4 Important Specifications of Switching Converter 35
2.4.1 Efficiency 35
2.4.2 Load and Line Regulation 36
2.4.3 Transient Response 37

Chapter 3 39
Structure of 20MHz Current Domain DC-DC Buck Converter 39
3.1 Proposed Current Domain 20MHz Buck Converter 39
3.1.1 Prior Art Conventional Current Mode Buck
Converter 39
3.1.2 Current Domain 20MHz Buck Converter 41
3.2 Small Signal Analysis and Compensation Scheme of
Current Domain DC-DC Buck Converter 42
3.2.1 Small Signal Analysis [5] 42
3.2.2 Structure of PI-Compensator 48
3.2.3 P-Compensator 50
3.3 Soft Start Technique 51
3.4 Output Inductor and Capacitor Selection 53

Chapter 4 55
Circuit Implementation and Simulation Results 55
4.1 P-Compensator 55
4.2 Current Sensing Circuit 59
4.3 Ramp Generator 63
4.4 Clock Generator 65
4.5 Current Comparator 71
4.6 Soft Start 73

Chapter5 75
System of High Switching DC-DC Buck Converter in Current Domain Control Simulation Results, Conclusions and Future Work 75
5.1 System Simulation Results 75
5.1.1 Start Up 75
5.1.2 Steady State of Output Voltage 77
5.1.3 Load Regulation 78
5.1.4 Line Regulation 78
5.1.5 Efficiency 79
5.1.6 Performance and Specification 80
5.2 Conclusions 81
5.3 Future Work 82

Reference 83

[1]D. Maksimovic, “Power Management Model and
Implementation of Power Management ICs for Next
Generation Wireless Applications,” Tutorial presented
at the International Conference on Circuits and System
(ISCAS), 2002.
[2]“Technical Review of Low Dropout Voltage Regulator
Operation and Performance,” Texas Instruments
Incorporated, Dallas, TX, Aug. 1999.
[3]P. Favrat, P. Deval and M. J. Declercq, ”A high-
efficiency CMOS Voltage Doubler,”IEEE Journal of Solid-
State Circuits, vol. 33, pp. 410-416, March. 1998.
[4]James S. Zeng, Lajos Burgyan, and Rendon A. Hollowa,
“Highly efficient step-down/step-up and step-up/step-
down charge pump,” United States Patent, Patent Number
6,657,875, July 16. 2002.
[5]Robert W. Erickson and Dragan Maksimovic, Fundamentals
of Power Electronics, 2nd ed., Norwell, MA: Kluwer
Academic Publishers, 2001.
[6]Cheung Fai Lee, Philip K. T.“A Monolithic Current-Mode
CMOS DC-DC Converter with On-Chip Current-Sensing
Technique,” IEEE Journal of Solid-State Circuits, vol.
39, pp. 3-13, Jan. 2004.
[7]Chi Yat Leung, Philip K.T. Mok, “A 1-V Integrated
Current-Mode Boost Converter in Standard 3.3 / 5-V CMOS
Technologies,” IEEE Journal of Solid-State Circuits,
Vol. 40, No. 11, pp. 2265-2274, Nov. 2005.
[8]Ding Ge, Zhiliang Chen, “On-chip boost DC-DC converter
in color OLED driver & controller ICs for mobile
application,” IEEE ASICON, vol. 1, pp. 459 – 463, Oct.
2005.
[9]Chi-Lin Chen, Wei-Lun Hsieh, Han-Hsiang Huang, Ke-Horng
Chen,“Fast Mode-Switching Technique in Hybrid-Mode
Operation,” The 51st Midwest Symposium on Circuits and
Systems, pp. 9-12, Aug. 2008.
[10]Peter Hazucha, Gerhard Schrom, Jaehong Hahn, Bradley A.
Bloechel, Paul Hack, Gregory E. Dermer, Siva Narendra,
Donald Gardner, Tanay Karnik, Vivek De, Shekhar
Borkar,” A 233-MHz 80%–87% Efficient Four-Phase DC–
DC Converter Utilizing Air-Core Inductors on Package,”
IEEE Journal of Solid-State Circuits, vol. 40, pp. 838-
845, April. 2005.
[11]Yu-Huei Lee, Shih-Jung Wang, Chun-Yu Hsieh, Ke-Horng
Chen,“Current mode DC-DC Buck Converters with Optimal
Fast-Transient Control”, IEEE International Symposium
on Circuits and Systems (ISCAS), pp. 3045-3048, May.
2008.
[12]Mossoba, J.T., Krein, P.T., “Small signal modeling of
Sensorless Current Mode Controlled DC-DC Converters,”
IEEE Workshop on Computers in Power Electronics,
Proceedings, pp. 23-28, June. 2002.
[13]Kaiwei Yao, et al., “Optimal Design of the Active
Droop Control Method for the Transient Response,” IEEE
APEC, vol. 2, pp. 718-723, Feb. 2003.
[14]Hollinger, W. and Punzenberger, M., “An Asynchronous
1.8MHz DC/DC Boost Converter Implemented in the Current
Domain for Cellular Phone Lighting Management,” IEEE
ESSCIRC, pp. 528-531, Sep. 2006.
[15]Shih-Min Chen, Chun-Yu Hsieh, Ke-Horng Chen, 0
“Challenge on Compact Size DC-DC Buck Converters with
High-Speed Current Sensor and On-Chip Inductors,” The
50th Midwest Symposium on Circuits and Systems
(MWSCAS), pp. 670-673, Aug. 2007.
[16]M.C. Di Piazza, A. Ragusa, G. and G. Tine, G. Vitale,
“A Soft Start Technique to Minimize EMI Implications in
Dual Voltage Vehicle Electrical System,” IEEE IECON,
vol. 2, pp. 1229-1234, Nov. 2002.
[17]Chun-Yu Hsieh, Yung-Chun Chuang, Ke-Horng Chen, ”A
Novel Precise Step-Shaped Soft-Start Technique for
Integrated DC-DC Converter,” The 14th IEEE
International Conference on Electronics, Circuits and
Systems (ICECS), pp. 771-774, Dec. 2007.
[18]Hirokazu Tsujimoto and Tetsuo Tateishi, “Soft starting
reference voltage circuit,” 6,348,833, Feb. 19, 2002.
[19]Padilla, I, Ramirez-Angulo, J., Carvajal, R.G., Lopez-
Martin, A.,”Highly Linear V/I Converter with
Programmable Current Mirrors,” IEEE International
Symposium on Circuits and Systems (ISCAS), pp. 941-944,
May. 2007.
[20]Lam, H.Y.H., Wing-Hung Ki , Dongsheng Ma,” Loop Gain
Analysis and Development of High-Speed High-Accuracy
Current Sensors for Switching Converters,” IEEE
International Symposium on Circuits and Systems
(ISCAS), vol. 5, May. 2004.
[21]Bryan A. Legates, “Low voltage current sense
amplifier,” United States Patent, Patent Number
5,969,574, October.19, 1999.
[22]Tsung-Yin Yu, “A High-Efficiency Synchronous CMOS
Switching Regulator with PWM/PFM-Mode Operation,”
National Chiao Tung University, Master of Electronics
Energineering, June. 2003.
[23]Abedinpour, S., Bakkaloglu, B., Kiaei, S., “A
Multistage Interleaved Synchronous Buck Converter With
Integrated Output Filter in 0.18 μm SiGe Process,”
IEEE Transactions on Power Electronics , vol, 22, Issue
6, pp. 2164 – 2175, Nov. 2007.
[24]B. Min and S. Kim, “High performance CMOS current
comparator using resistive feedback network,”
Electron. Lett, vol. 34, no. 22, pp. 2074–2076, 1998.
[25]Lu Chen, Bingxue Shi, Chun Lu, “A Robust High-Speed
and Low-Power CMOS Current Comparator Circuit,” The
2000 IEEE Asia-Pacific Conference on Circuits and
Systems, pp. 174-177, Dec. 2000.