臺灣博碩士論文加值系統

本論文提出一個可應用於紅外線感測器(IR Focal Plane Arrays)與需要固定偏壓感測元件的脈衝寬度調變(Pulse Width Modulation)讀出電路，具有良好功率消耗(Good Power Efficiency)與高動態範圍(High Dynamic Range)特性，並達成固定圖像雜訊消除(Fixed Pattern Noise Reduction)與感光區間調變(Sensitive Range Tuning)功能。
為了達到良好的功率消耗表現，本論文所提出的電容反饋跨阻抗放大器(Capacitive Trans-impedance Amplifier)配合脈衝寬度調變讀出電路，將操作電壓由傳統紅外線感測器的3.3伏特降至1.5伏特。並且在曝光操作上使用了雙重曝光延續計算(Dual-Exposure Extended-Counting)技巧，成功克服傳統脈衝寬度調變讀出感測器，其曝光時間受到操作方式限制的問題。除了動態範圍延展，好的影像品質也必須兼具，因此在電路中利用耦合電容，實作出自動歸零與偏移電壓消除(Auto Zeroing & Offset Cancellation)機制來消除固定圖像雜訊。另外提出一個時間控制自動對其斜坡電壓(Aligned Time-Control Ramp)產生器，提供一個可調變斜率的閥值電壓(Threshold Voltage)供給脈衝寬度調變操作，達成感光區間調整的功能。
為驗證本電路，此架構使用0.18微米1P6M互補式金氧半導體製程製作，晶片總面積為1700×1800μm2，擁有64X64像素陣列並搭載上述構想的讀出電路原型，操作於類比端1.5伏特，數位端0.8伏特電壓下。量測驗證成果，此提出的高動態範圍讀出電路架構達到132dB的動態範圍，成功降低固定圖像雜訊至0.24%rms，230張的每秒顯示幀數，同時擁有1.27nW/frame ∙ pixel的功率消耗表現。

This thesis presents a good power efficiency and high dynamic range (HDR) Readout IC with pulse width modulation (PWM) for infrared focal plane arrays (IRFPAs) and the fixed bias needed sensors. The fixed pattern noise (PFN) reduction has been implemented and the sensitive range tuning function is available.
To achieve good power efficiency, the proposed capacitive trans-impedance amplifier (CTIA) with PWM readout circuit lower the operating voltage from 3.3V of conventional IR sensor to 1.5V. The operation of dual-exposure extended-counting (DEEC) exposure control overcome the limited exposure time issue of conventional PWM imager. Beside the dynamic range extension, fine image quality is also required. Hence, in order to implement the auto zeroing & offset cancellation (AZOC) mechanism, a coupling capacitance is added on the readout circuit to eliminate the FPN. Aligned time-control ramp (ATCR) generator is also developed and provides a tunable slope ramp threshold voltage for PWM readout operation which can achieve the sensitive range tuning function.
A prototype of 64×64 pixel imager employed these schemes has been designed and fabricated in 0.18um 1P6M CMOS technology with a chip area of 1700×1800μm2, operating under 1.5V for analog and 0.8V for digital. The measurement result shows the proposed HDR ROIC achieves 132dB dynamic range, below 0.24%rms FPN performance, 230fps frame rate and resulting 1.27nW/frame ∙ pixel power efficiency.

Abstract ii
Content iii
List of Figures vi
List of Tables ix
Chapter 1 Introduction 1
1.1 Motivation 1
1.2 Thesis Contribution 2
1.3 Thesis Organization 4
Chapter 2 Background Information 5
2.1 Characteristic of IR Detector 6
2.2 Architecture Selection 7
2.2.1 Review on Capacitive Trans-Impedance Amplifier 7
2.2.2 Dynamic Range Extension for IRFPAs 8
2.3 Design Consideration of CTIA+PWM ROIC 18
2.3.1 Exposure Time 19
2.3.2 Non-Ideal Effects 20
2.3.3 Pixel Area and Power Consumption 22
2.4 Sensitive Range Tuning 22
2.4.1 Tuning Concept 23
2.4.2 Tuning Issues 24
2.5 Summary 25
Chapter 3 High Dynamic Range CTIA+PWM readout with AZOC and ATCR 27
3.1 Dual Exposure Extended Counting [17] 27
3.2 Auto Zeroing & Offset Cancellation 29
3.3 Aligned Time Control Ramp 31
3.4 Summary 32
Chapter 4 Prototype Implementation of HDR ROIC 33
4.1 System Architecture of Proposed ROIC 33
4.2 In-Pixel Circuit 35
4.2.1 In-Pixel CDS with AZOC 35
4.2.2 CTIA Design 37
4.2.3 Column Buffer 38
4.3 Column Pulse to Digital Converter 39
4.3.1 Comparator 40
4.3.2 10b Counter and Latch 41
4.3.3 Level Shifter 42
4.4 Global ATCR Generator 42
4.4.1 Integrator 43
4.4.2 Bi-directional Current Source 44
4.4.3 Unity Gain Buffer 46
4.5 Column and Row Controls 46
4.6 Chip Operation 47
4.7 Summary 49
Chapter 5 Measurement Results 50
5.1 Chip Implementation 50
5.2 Measurement Environment Setup 52
5.3 Dynamic Range Extension 54
5.3.1 Lux Transfer Curve Response 55
5.3.2 Captured Images 56
5.4 Fixed Pattern Noise Reduction 58
5.4.1 Lux Transfer Curve Response 58
5.4.2 Captured Images 60
5.5 Sensitive Range Tuning Function 61
5.5.1 Lux Transfer Curve Response 61
5.5.2 Captured Images 62
5.6 Temporal Noise Measurement 63
5.7 Performance Summary and Comparison 64
Chapter 6 Conclusion and Future Work 65
6.1 Conclusion 65
6.2 Future Work 66
Bibliography 68

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