切換電容式電壓轉換器之電路分析

Abstract

隨著半導體製程的演進，如0.35微米，0.25微米，0.18微米，0.13微米，甚至是40奈米，20奈米的發展，積體電路也隨著製成的演進面積越來越小，而隨著裝置的縮小，電源供應電壓也隨之降低為了可以解決功率消耗的問題。具有高功率轉換效率功率管理模組可與其他功能模組完整的整合於單一晶片而達到面積的最佳使用效率的技術是必不可少的。為了提供具有較大負載範圍的供應電流，使用基於電感的切換式DC-DC轉換器廣泛的在SoC應用中使用[1]。然而，成本較高的電感器需要使用大量的印刷電路板（PCB）面積，使用電感式的DC-DC轉換器較難進一步降低功率管理模組的尺寸，特別是對於SoC系統的應用上。此外，容易被磁性元件衍生出的電磁干擾（EMI），往往成為在SoC應用的棘手問題。一些特殊應用的積體電路，例如電子抹除式可複寫唯讀記憶體（EEPROM），快閃儲存器，動態隨機存取存儲器（DRAM）和TFT-LCD驅動器需要較高的供應電壓才能有正常功能操作，針對這類特殊應用的積體電路之電壓要求，電源管理模組的切換式電容式（Switch-Capacitor）轉換器是另一選擇。 切換式電容式（Switch-Capacitor）轉換器具有多項優點，體積小，操作簡便的控制方案及低EMI特性，和中等功率轉換效率[2] - [6]。 切換式電容式（Switch-Capacitor）轉換器已被用來產生相較於系統電壓較高或較低的供應電壓供給於內部電路。它具有低電磁干擾（EMI），且電感少，效率大於90％，成本低，以及較小的使用面積。因此，目前成為了手持的TFT-LCD驅動器最好的選擇之一。許多不同的拓撲結構被提出近年來[6] [7] [8]。在一開始的時候，倍壓和高壓變頻器將介紹基本的了解和獲得更深入地了解操作原理。在之後的章節，涉及到的SC電壓轉換器的基本概念 [9]及倍壓轉換器和逆變器電壓轉換器將詳細介紹，接著會在本文中所提出的新架構之切換式電容式轉換器介紹及比較。

With the progress of semiconductor process from submicron meter to deep submicron meter such as 0.35μm, 0.25μm, 0.18μm, 0.13μm and even 40nm, the devices are made smaller generation by generation, and the power supply voltage levels for the smaller devices also drop generation by generation for solving power dissipation issues.Power management modules with high power conversion efficiency and fully integration in SoC for a compact size is essential for advanced electronic devices. To provide the supply current with a wide load range, the inductor-based switching DC-DC converter is commonly used in SoC applications [1]. However, due to large occupation of print-circuit-board (PCB) area and high cost resulted from inductor, it is hard to further reduce the size of power management module especially for SoC system applications. Furthermore, Electromagnetic interference (EMI), which is easily derived with the magnetic components, often becomes the thorny issue in the SoC applications. Some special application ICs such as the electrically erasable programmable read-only memory (EEPROM), the flash memories, the dynamic random access memory (DRAM) and the TFT-LCD drivers need high voltages for normal function operation. Alternative selection of power management modules is switched capacitor (SC) regulators. SC DC-DC converters have the features of small size, simple control scheme, low EMI, and the moderate power conversion efficiency [2]-[6]. SC voltage converter has been used to generate supplying voltage higher or lower than the system power supply voltage. It features low electromagnetic interference (EMI), inductor-less, high efficiency larger than 90%, low cost, low profile, and compact size. Thus, it becomes one of best choices in the handheld TFT-LCD drivers. Many different topologies were presented in recent years [6] [7] [8]. In the beginning, voltage doubler and voltage inverter will be introduced for basic understanding and gaining more insight into the operation theory. In the folllwing subsections, basic concepts related to SC voltage converters will be given [9]. In sequence, voltage doubler converter and voltage inverter converter will be reviewed in details. A new proposed method of the dual side dual output switching capacitor voltage converter that generates DDVDH and VCL with only 2 flying capacitors and 12 power switches will be discussed.