臺灣博碩士論文加值系統

在汽車應用中，通過砷化鎵場效電晶體控制方法的短雷射脈衝寬度和有效保證精確的雷射脈衝是高解析度光達系統中的主要挑戰。有兩種主要的雷射二極體驅動電路用於脈衝光達系統應用。首先，在電容器放電驅動電路中，接受寄生電感的好控制脈衝簡化了控制。但是，固定的雷射脈衝會導致脈衝寬度的無效調變並且限制了距離解析度。在高脈衝重複頻率下，不完整脈衝和不足的功率將減小有效檢測範圍，因為在每個命令周期的關閉期間，總線電壓接近百伏特。另一個具有低電源電壓的場效電晶體控制驅動器允許複雜的命令序列，然而此架構需要電流檢測和總線電壓控制，以確保脈衝到脈衝的可重複性。此外，此電路必須足夠慢地切換，以使寄生電感不會顯著降低波形。
為防止元件損壞，傳統的柵極電阻限制了開關頻率並增加損耗。另一種自適應三斜率柵極驅動器會受到製程、電壓及溫度變化的影響，並且下降斜率是不確定的，這會導致上升時間和下降時間的不平衡並使雷射脈衝失真。
因此，本論文提出了一種用於光達系統的數位型砷化鎵場效電晶體驅動器，具有雷射二極體頂點電流校正技術和電流脈衝平衡器迴圈。即使在功率路徑中存在寄生電阻的變化，雷射二極體頂點電流校正技術在最高200MHz脈衝重複頻率下，可通過調整總線電壓來確保恆定的28A電流脈衝，從而提高脈衝到脈衝的可靠性。另外，利用所提出的非同步二進制驅動器，電流脈衝平衡器優化驅動器速度，並將脈衝寬度減小到0.9ns。為防止電流脈衝失真，電流脈衝平衡器將電流脈衝上升時間和下降時間在30ns內皆平衡至0.2ns。

In automotive applications, short laser pulse ILASER widths through GaN FET control methods and effective assurance of accurate ILASER are major challenges in high-resolution light detection and ranging (LiDAR) systems. There are two main laser-diode driver circuits for pulsed LiDAR applications. First, a well-controlled pulse that accepts the parasitic inductance simplifies control in capacitor discharge driver circuit. But, the fixed ILASER results in an ineffective modulation of the pulse width and limits the distance resolution. Under a high pulse repetition frequency (PRF), incomplete pulses and insufficient power will reduce the effective detection range since the bus voltage is near hundred volts during the off time of each command cycle. The other FET control driver with a low supply voltage allows complex command sequences, while the structure needs current sensing and bus voltage control to ensure pulse-to-pulse repeatability. Furthermore, the circuit must switch slowly enough that stray inductance does not significantly degrade the waveforms.
To prevent the device being damaged, the conventional gate resistor limits the switching frequency and increases losses. The other adaptive triple-slope gate driver is not free from process, voltage, and temperature (PVT) variations and the falling slope is indeterminate, which induces imbalance between rise time and fall time and distorts ILASER.
Therefore, this thesis proposes a digital-type GaN driver with a laser diode peak current correction (LDPCC) technique and a current pulse balancer (CPB) loop for LiDAR systems. Even with parasitic resistance changes in the power path, the LDPCC ensures a constant 28A ILASER by adjusting the bus voltage under 200MHz maximum PRF to enhance pulse-to-pulse reliability. In addition, with the proposed asynchronous binary driver (ABD), the CPB optimizes driver speed, and reduces pulse width to 0.9ns. To prevent ILASER distortion, the CPB balances ILASER rise time and fall time to 0.2ns in 30ns.

摘 要 i
ABSTRACT ii
誌 謝 iii
Contents iv
Figure Captions v
Table Captions vii
Chapter 1 Introduction 1
1.1 Laser Diode Drivers in Light Detection and Ranging (LiDAR) 1
1.2 Gallium Nitride (GaN) FETs in Laser Diode Drivers 5
1.3 Motivation 7
1.4 Thesis Organization 8
Chapter 2 Prior Arts for Laser Diode Drivers and GaN Driving Control 9
2.1 Capacitor Discharge Driver and FET Control Driver 9
2.2 Dual SR Control and Adaptive Tri-Slope Gate Driving 12
Chapter 3 Proposed Digital-Type GaN Driver for LiDAR Systems 16
3.1 Architecture of Proposed Digital-Type GaN Driver 16
3.2 Laser Diode Peak Current Correction 18
3.3 Current Pulse Balancer Loop 19
Chapter 4 Circuit Implementations 22
4.1 Laser Diode Peak Current Correction 22
4.2 Current Pulse Balancer Loop 24
4.2.1 Current Pulse Balancer 24
4.2.2 Asynchronous Binary Driver 26
Chapter 5 Experimental Results 29
5.1 Chip micrograph 29
5.2 Adjusted VBUS for Constant Peak Current with the LDPCC Technique 30
5.3 Transient Performances with the CPB Loop 31
5.4 VG and ILASER with Different Driving Capability of the ABD 32
5.5 Comparison Table 34
Chapter 6 Conclusion and Future Work 35
Reference 36

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