現今，以互補式金氧半電晶體製程所製作的溫度感測計已大量地使用在電腦相關的應用上。一般來說，此種溫度感測計的準確度大多受限於溫度感測元件特性、溫度感測計的電路架構以及在溫度感測計中非理想效應。這些非理想效應包括了電路中元件的不匹配效應、因製程參數的絕對值等效偏移之影響與運算放大器的偏移電壓。這些因素對溫度感測計的精準度都有顯著的影響。所以，本論文探討了兩種典型溫度感測器的設計原理並提出如何利用電路設計以減少非理想效應的影響。本論文提出一利用電路設計技巧能達到高準確度之溫度感測計。此種溫度感測計利用二次曲線修正和線性片段修正技巧可有效的提升溫度感測計的精準度，並且利用動態偏移消除電路改善非理想效應的影響。在假設1% 的元件不匹配效應、10％的元件絕對值偏移和1mV的運算放大器偏移電壓，此溫度感測計在-55□C到125□C的範圍內，其準確度預期能達到0.2□C。這樣的精準度將使溫度感測計的應用更為廣泛。

CMOS temperature sensors have been used extensively in the computer-based applications. The accuracy level of a CMOS temperature sensor is limited by the temperature sensing device, circuit schemes and non-idealities such as mismatches in components, absolute variations and offset voltage in Op-amplifier. These factors usually affect the accuracy of sensors most. Accordingly, the accuracy level and non-idealities of typical voltage-base and current-base temperature sensors are analyzed in detail. This study provides guidelines for designing a high-accuracy temperature sensor. Based on these guidelines, a high-accuracy temperature sensor design is proposed. This design adopts second-order correction and piece-wise-linear techniques to reduce the error caused by the non-linear characteristics of a BJT device. Furthermore, dynamic offset-cancellation techniques are used to reduce the error caused by non-ideal factors in the sensor. By injecting 1% mismatch and 10% absolute variation in various components and 1mV Op-Amp offset voltage in the sensor, this temperature sensor has the best expected accuracy of 0.3°C from -55°C to 125°C. This result is sufficient to expand the applications of CMOS temperature sensors to high precision applications.

LIST OF CONTENTS
English Abstract i
Chinese Abstract ii
Acknowledgement iii
List of Contents iv
List of Figures vii
List of Tables ix
Chapter 1 Introduction 1
1.1 Background and Motivation 1
1.2 Organization 2
Chapter 2 Review 3
2.1 Fundamentals 3
2.2 Accuracy of Temperature Sensors 4
2.3 Device Characteristic 6
2.3.1 Temperature Sensing Devices 6
2.3.2 Temperature Characteristics of Bipolar Transistors 7
2.3.3 Ultimate Accuracy Limitation of Bipolar Transistors 9
2.4 Offset Cancellation Techniques in Temperature Sensors10
2.4.1 Chopper Stabilization 10
2.4.2 Dynamic Element Matching Technique 12
2.5 Summary 13
Chapter 3 Temperature Sensor Circuits 25
3.1 Voltage-base Temperature Sensor 25
3.1.1 Bandgap Reference Voltage Generator 25
3.1.2 PTAT Voltage Generator 27
3.1.3 Ideal Simulation Results 28
3.2 Non-idealities of Voltage-base Temperature Sensors 28
3.2.1 Mismatch between BJTs 29
3.2.2 Absolute Variation in BJT 31
3.2.3 Mismatch in R1 32
3.2.4 Mismatch in R2A 33
3.2.5 Mismatch in R2B 34
3.2.6 Absolute Variation in Resistances 34
3.2.7 Offset Voltage in Smplifier 35
3.2.8 Non-idealities in Instrumental Amplifier 36
3.2.9 Summary 37
3.3 Current-base Temperature Sensor 38
3.3.1 PTAT Current and Bandgap Reference Current
Generators 39
3.3.2 Analog-to-Digital Converter 41
3.4 Non-idealities of Current-base Temperature Sensors 44
3.4.1 Mismatch in IBIAS1 and IBIAS2 44
3.4.2 Variation in the Absolute Level of the Bias
Currents 44
3.4.3 Effects of Mismatch and absolute variation in BJTs 46
3.4.4 Mismatch in resistances 47
3.4.5 Absolute Variation in Resistances 48
3.4.6 Mismatch in Current-Mirrors 49
3.4.7 Offset Voltage 49
3.4.8 Summary 50
3.5 Comparison 52
Chapter 4 High-Accuracy Temperature Sensor Design 73
4.1 Motivation 73
4.2 Design Idea 74
4.2.1 Second-order Correction 74
4.2.2 Piece-wise-linear Correction 75
4.3 Implementation 76
4.4 Ideal Simulation 77
4.5 Circuits Architecture 77
4.5.1 PTAT Current Generator 78
4.5.2 IEB Generator 78
4.6 Summary 79
Chapter 5 Conclusion and Future Work 93
5.1 Conclusions 94
5.2 Future Work 94
REFERENCE 96

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