臺灣博碩士論文加值系統

Beamforming is a signal processing technique used in sensor arrays. After specific time delay, signal will be constructive interference or destructive interference. Beamforming used in many applications, ex: biomedical ultrasound imaging system, communication transmit system, sonar detection system, etc. By using 0.18-μm CMOS process, two circuits are implemented in this thesis. The first chapter introduces the fundamentals of a true-time delay beamforming system. Chapter 2 illustrates the basics and challenges in true-time delay beamforming design and the link budget calculation is demonstrated for system optimization.
In Chapter 3, an analog beamforming front-end circuit, including amplifiers, an adder and an analog-to-digital converter, is implemented by using a 0.18-μm CMOS process.
In Chapter 4, a power saving and rotatable beamforming analog front-end is implemented by using a 0.18-μm CMOS process. Finally, a conclusion of this thesis is made in Chapter 5.

摘要 I
Abstract III
Table of Contents V
List of Figures VII
List of Tables X
Chapter 1 Introduction 1
1.1 Motivation 1
1.2 Thesis overview 5
Chapter 2 Background 7
2.1 Introduction of Human Voice 7
2.2 Introduction of beamforming microphone 8
2.2.1 Microphone specifications 10
Sensitivity 10
Directionality 11
Signal-to-noise ratio (SNR) 11
Equivalent input noise (EIN) 12
Dynamic Range (DR) 13
2.2.2 Beamforming microphone 14
2.3 Techniques for eliminating op-amp imperfections 18
2.4 Fundamentals of ADC 20
2.5 Link budget 23
2.6 Introduction of directional microphone 25
Chapter 3 A Three-channel True-time Delay Beamforming Analog Front-end 29
3.1 Introduction 29
3.2 Proposed Architecture 30
3.3 Circuit Implementation of Proposed Interface Circuits 32
3.3.1 Constant-transconductance bias circuit 32
3.3.2 Single-to-Differential Amplifier 35
3.3.3 Fully Differential Chopper Amplifier 36
3.3.4 True-time Delay Beamforming 41
3.3.5 Analog-to-Digital Converter 44
3.4 Experimental Results 47
3.5 Conclusion 53
Chapter 4 A Rotatable and Power Saving True-time Delay Beamforming Analog Front-end 55
4.1 Introduction 56
4.2 Proposed Architecture 57
4.3 Circuit Implementation of Proposed Interface Circuits 58
4.3.1 System overview 58
4.3.2 True-time Delay Beamforming 59
4.4 Measurement Results 63
4.5 Conclusion 71
Chapter 5 Conclusion 73
Bibliography 74

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