使用調節脈衝電流的積體化發光單元

Abstract

本論文提出一個使用可調節脈衝電流的積體化發光單元應用於低功率系統。在本論文，作者將一個白光發光二極體和一個可調節脈衝電流驅動電路結合封裝在同一個晶片，稱之為一個積體化的發光單元。這樣的結合將可以節省封裝成本以及元件體積並且增加了發光密度。此外，脈衝電流直接驅動發光二極體而避免經過多層的封裝，因此可以降低寄生效應。此發光單元以參考文獻和相關理論為基礎，以磅線連接發光二極體與驅動電路並且採用垂直堆疊的結構，達到較佳的發光效率與較低的接面溫度。白色發光二極體使用藍色發光二極體與黃色螢光粉所合成，驅動電路使用0.5微米互補式金屬氧化物半導體製程實現。此驅動電路有兩個控制訊號用來調節脈衝電流，其中一個控制訊號可調節脈衝電流的峰值；另一個控制訊號可用來調節脈衝電流的操作頻率。此驅動電路只需要一個感測電阻完成閉迴路控制而不需要任何的補償電容維持系統穩定。此積體化的發光單元優點為體積小、低功耗、可靠度高以及壽命長，因此適合應用於可攜式的系統中。本論文將詳述可調節脈衝電流驅動電路之基本操作原理，並搭配實驗結果來驗證所提架構之可行性。

This dissertation presents an integrated lighting unit with regulated pulse current for low-power application. A white LED with a regulated pulse current driver integrated in one chip, which is named a lighting unit in this dissertation. Such a combination reduces the packaging costs and the size of the device as well as increases the luminous density. In addition, as the pulse current is directly driven without passing through multiple packages, the parasitic effects can be greatly reduced. Based on previous literatures and the relative theory, we develop a lighting unit by bonding the LED and its driver with a wire interconnection and with vertical stack integration architecture to achieve better luminous efficacy and lower junction temperature. The white LED is synthesized by a blue LED with yellow phosphor and this driver is fabricated with 0.5μm CMOS process. Two control signals are used in the proposed driver to modulate the pulse current. One signal modulates the amplitude of pulse current and the other modulates the pulse current frequency. The proposed driver only needs a sensing resistor for a closed loop without other compensation capacitors for stability consideration. This lighting unit has several advantages, such as compact size, low power consumption, high reliability and long lifetime. Therefore, it is suitable for portable application. In this dissertation, the basic operating principles of the regulated pulse current driver are described in detail, along with some experimental results to verify the feasibility of the proposed scheme.